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An accordion is a string (yes, in the real world accordions are musical instruments, but let's forget about it for a while) which can be represented as a concatenation of: an opening bracket (ASCII code $091$), a colon (ASCII code $058$), some (possibly zero) vertical line characters (ASCII code $124$), another colon, ...
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Anton has the integer x. He is interested what positive integer, which doesn't exceed x, has the maximum sum of digits. Your task is to help Anton and to find the integer that interests him. If there are several such integers, determine the biggest of them. -----Input----- The first line contains the positive inte...
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Apart from having lots of holidays throughout the year, residents of Berland also have whole lucky years. Year is considered lucky if it has no more than 1 non-zero digit in its number. So years 100, 40000, 5 are lucky and 12, 3001 and 12345 are not. You are given current year in Berland. Your task is to find how long...
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You have a long fence which consists of $n$ sections. Unfortunately, it is not painted, so you decided to hire $q$ painters to paint it. $i$-th painter will paint all sections $x$ such that $l_i \le x \le r_i$. Unfortunately, you are on a tight budget, so you may hire only $q - 2$ painters. Obviously, only painters yo...
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Jamie loves sleeping. One day, he decides that he needs to wake up at exactly hh: mm. However, he hates waking up, so he wants to make waking up less painful by setting the alarm at a lucky time. He will then press the snooze button every x minutes until hh: mm is reached, and only then he will wake up. He wants to kno...
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Luba is surfing the Internet. She currently has n opened tabs in her browser, indexed from 1 to n from left to right. The mouse cursor is currently located at the pos-th tab. Luba needs to use the tabs with indices from l to r (inclusive) for her studies, and she wants to close all the tabs that don't belong to this se...
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You are fighting with Zmei Gorynich — a ferocious monster from Slavic myths, a huge dragon-like reptile with multiple heads! $m$ Initially Zmei Gorynich has $x$ heads. You can deal $n$ types of blows. If you deal a blow of the $i$-th type, you decrease the number of Gorynich's heads by $min(d_i, curX)$, there $cur...
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Anton likes to listen to fairy tales, especially when Danik, Anton's best friend, tells them. Right now Danik tells Anton a fairy tale: "Once upon a time, there lived an emperor. He was very rich and had much grain. One day he ordered to build a huge barn to put there all his grain. Best builders were building that ba...
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Tokitsukaze is playing a game derivated from Japanese mahjong. In this game, she has three tiles in her hand. Each tile she owns is a suited tile, which means it has a suit (manzu, pinzu or souzu) and a number (a digit ranged from $1$ to $9$). In this problem, we use one digit and one lowercase letter, which is the fir...
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Yet another round on DecoForces is coming! Grandpa Maks wanted to participate in it but someone has stolen his precious sofa! And how can one perform well with such a major loss? Fortunately, the thief had left a note for Grandpa Maks. This note got Maks to the sofa storehouse. Still he had no idea which sofa belongs ...
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On the planet Mars a year lasts exactly n days (there are no leap years on Mars). But Martians have the same weeks as earthlings — 5 work days and then 2 days off. Your task is to determine the minimum possible and the maximum possible number of days off per year on Mars. -----Input----- The first line of the input ...
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Little Joty has got a task to do. She has a line of n tiles indexed from 1 to n. She has to paint them in a strange pattern. An unpainted tile should be painted Red if it's index is divisible by a and an unpainted tile should be painted Blue if it's index is divisible by b. So the tile with the number divisible by a a...
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Vova has won $n$ trophies in different competitions. Each trophy is either golden or silver. The trophies are arranged in a row. The beauty of the arrangement is the length of the longest subsegment consisting of golden trophies. Vova wants to swap two trophies (not necessarily adjacent ones) to make the arrangement a...
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Now you can take online courses in the Berland State University! Polycarp needs to pass k main online courses of his specialty to get a diploma. In total n courses are availiable for the passage. The situation is complicated by the dependence of online courses, for each course there is a list of those that must be pas...
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Let's suppose you have an array a, a stack s (initially empty) and an array b (also initially empty). You may perform the following operations until both a and s are empty: Take the first element of a, push it into s and remove it from a (if a is not empty); Take the top element from s, append it to the end of arr...
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Vasya likes everything infinite. Now he is studying the properties of a sequence s, such that its first element is equal to a (s_1 = a), and the difference between any two neighbouring elements is equal to c (s_{i} - s_{i} - 1 = c). In particular, Vasya wonders if his favourite integer b appears in this sequence, that ...
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A string is called bracket sequence if it does not contain any characters other than "(" and ")". A bracket sequence is called regular if it it is possible to obtain correct arithmetic expression by inserting characters "+" and "1" into this sequence. For example, "", "(())" and "()()" are regular bracket sequences; ")...
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Arpa is researching the Mexican wave. There are n spectators in the stadium, labeled from 1 to n. They start the Mexican wave at time 0. At time 1, the first spectator stands. At time 2, the second spectator stands. ... At time k, the k-th spectator stands. At time k + 1, the (k + 1)-th spectator stands and th...
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Petya recieved a gift of a string s with length up to 10^5 characters for his birthday. He took two more empty strings t and u and decided to play a game. This game has two possible moves: Extract the first character of s and append t with this character. Extract the last character of t and append u with this charact...
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Polycarp has recently created a new level in this cool new game Berlio Maker 85 and uploaded it online. Now players from all over the world can try his level. All levels in this game have two stats to them: the number of plays and the number of clears. So when a player attempts the level, the number of plays increases...
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Karen is getting ready for a new school day! [Image] It is currently hh:mm, given in a 24-hour format. As you know, Karen loves palindromes, and she believes that it is good luck to wake up when the time is a palindrome. What is the minimum number of minutes she should sleep, such that, when she wakes up, the time...
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Nicholas has an array a that contains n distinct integers from 1 to n. In other words, Nicholas has a permutation of size n. Nicholas want the minimum element (integer 1) and the maximum element (integer n) to be as far as possible from each other. He wants to perform exactly one swap in order to maximize the distance...
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Let's call a string "s-palindrome" if it is symmetric about the middle of the string. For example, the string "oHo" is "s-palindrome", but the string "aa" is not. The string "aa" is not "s-palindrome", because the second half of it is not a mirror reflection of the first half. [Image] English alphabet You are given...
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You are given two positive integer numbers a and b. Permute (change order) of the digits of a to construct maximal number not exceeding b. No number in input and/or output can start with the digit 0. It is allowed to leave a as it is. -----Input----- The first line contains integer a (1 ≤ a ≤ 10^18). The second lin...
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Alice and Bob play 5-in-a-row game. They have a playing field of size 10 × 10. In turns they put either crosses or noughts, one at a time. Alice puts crosses and Bob puts noughts. In current match they have made some turns and now it's Alice's turn. She wonders if she can put cross in such empty cell that she wins imm...
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You are given matrix with n rows and n columns filled with zeroes. You should put k ones in it in such a way that the resulting matrix is symmetrical with respect to the main diagonal (the diagonal that goes from the top left to the bottom right corner) and is lexicographically maximal. One matrix is lexicographically...
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Wet Shark asked Rat Kwesh to generate three positive real numbers x, y and z, from 0.1 to 200.0, inclusive. Wet Krash wants to impress Wet Shark, so all generated numbers will have exactly one digit after the decimal point. Wet Shark knows Rat Kwesh will want a lot of cheese. So he will give the Rat an opportunity to ...
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You are given a string s consisting of n lowercase Latin letters. You have to type this string using your keyboard. Initially, you have an empty string. Until you type the whole string, you may perform the following operation: add a character to the end of the string. Besides, at most once you may perform one addit...
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The All-Berland National Olympiad in Informatics has just ended! Now Vladimir wants to upload the contest from the Olympiad as a gym to a popular Codehorses website. Unfortunately, the archive with Olympiad's data is a mess. For example, the files with tests are named arbitrary without any logic. Vladimir wants to re...
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Luba has a ticket consisting of 6 digits. In one move she can choose digit in any position and replace it with arbitrary digit. She wants to know the minimum number of digits she needs to replace in order to make the ticket lucky. The ticket is considered lucky if the sum of first three digits equals to the sum of las...
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The campus has $m$ rooms numbered from $0$ to $m - 1$. Also the $x$-mouse lives in the campus. The $x$-mouse is not just a mouse: each second $x$-mouse moves from room $i$ to the room $i \cdot x \mod{m}$ (in fact, it teleports from one room to another since it doesn't visit any intermediate room). Starting position of ...
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ZS the Coder has recently found an interesting concept called the Birthday Paradox. It states that given a random set of 23 people, there is around 50% chance that some two of them share the same birthday. ZS the Coder finds this very interesting, and decides to test this with the inhabitants of Udayland. In Udayland,...
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In this problem we assume the Earth to be a completely round ball and its surface a perfect sphere. The length of the equator and any meridian is considered to be exactly 40 000 kilometers. Thus, travelling from North Pole to South Pole or vice versa takes exactly 20 000 kilometers. Limak, a polar bear, lives on the N...
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You are given two arithmetic progressions: a_1k + b_1 and a_2l + b_2. Find the number of integers x such that L ≤ x ≤ R and x = a_1k' + b_1 = a_2l' + b_2, for some integers k', l' ≥ 0. -----Input----- The only line contains six integers a_1, b_1, a_2, b_2, L, R (0 < a_1, a_2 ≤ 2·10^9, - 2·10^9 ≤ b_1, b_2, L, R ≤ 2·...
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It's New Year's Eve soon, so Ivan decided it's high time he started setting the table. Ivan has bought two cakes and cut them into pieces: the first cake has been cut into a pieces, and the second one — into b pieces. Ivan knows that there will be n people at the celebration (including himself), so Ivan has set n plat...
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The flag of Berland is such rectangular field n × m that satisfies following conditions: Flag consists of three colors which correspond to letters 'R', 'G' and 'B'. Flag consists of three equal in width and height stripes, parralel to each other and to sides of the flag. Each stripe has exactly one color. Each col...
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Ayrat is looking for the perfect code. He decided to start his search from an infinite field tiled by hexagons. For convenience the coordinate system is introduced, take a look at the picture to see how the coordinates of hexagon are defined: [Image] [Image] Ayrat is searching through the field. He started at point (...
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Dante is engaged in a fight with "The Savior". Before he can fight it with his sword, he needs to break its shields. He has two guns, Ebony and Ivory, each of them is able to perform any non-negative number of shots. For every bullet that hits the shield, Ebony deals a units of damage while Ivory deals b units of dama...
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Running with barriers on the circle track is very popular in the country where Dasha lives, so no wonder that on her way to classes she saw the following situation: The track is the circle with length L, in distinct points of which there are n barriers. Athlete always run the track in counterclockwise direction if you...
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A string is a palindrome if it reads the same from the left to the right and from the right to the left. For example, the strings "kek", "abacaba", "r" and "papicipap" are palindromes, while the strings "abb" and "iq" are not. A substring $s[l \ldots r]$ ($1 \leq l \leq r \leq |s|$) of a string $s = s_{1}s_{2} \ldots ...
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Is it rated? Here it is. The Ultimate Question of Competitive Programming, Codeforces, and Everything. And you are here to answer it. Another Codeforces round has been conducted. No two participants have the same number of points. For each participant, from the top to the bottom of the standings, their rating before ...
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You are given the array of integer numbers a_0, a_1, ..., a_{n} - 1. For each element find the distance to the nearest zero (to the element which equals to zero). There is at least one zero element in the given array. -----Input----- The first line contains integer n (1 ≤ n ≤ 2·10^5) — length of the array a. The sec...
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You are given a binary string $s$. Find the number of distinct cyclical binary strings of length $n$ which contain $s$ as a substring. The cyclical string $t$ contains $s$ as a substring if there is some cyclical shift of string $t$, such that $s$ is a substring of this cyclical shift of $t$. For example, the cyclic...
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You are given the set of vectors on the plane, each of them starting at the origin. Your task is to find a pair of vectors with the minimal non-oriented angle between them. Non-oriented angle is non-negative value, minimal between clockwise and counterclockwise direction angles. Non-oriented angle is always between 0 ...
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Vasiliy has a car and he wants to get from home to the post office. The distance which he needs to pass equals to d kilometers. Vasiliy's car is not new — it breaks after driven every k kilometers and Vasiliy needs t seconds to repair it. After repairing his car Vasiliy can drive again (but after k kilometers it will ...
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You are given positive integer number n. You should create such strictly increasing sequence of k positive numbers a_1, a_2, ..., a_{k}, that their sum is equal to n and greatest common divisor is maximal. Greatest common divisor of sequence is maximum of such numbers that every element of sequence is divisible by the...
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After finishing eating her bun, Alyona came up with two integers n and m. She decided to write down two columns of integers — the first column containing integers from 1 to n and the second containing integers from 1 to m. Now the girl wants to count how many pairs of integers she can choose, one from the first column ...
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You are given an array $a$ consisting of $n$ integers. Beauty of array is the maximum sum of some consecutive subarray of this array (this subarray may be empty). For example, the beauty of the array [10, -5, 10, -4, 1] is 15, and the beauty of the array [-3, -5, -1] is 0. You may choose at most one consecutive subarr...
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Bizon the Champion isn't just charming, he also is very smart. While some of us were learning the multiplication table, Bizon the Champion had fun in his own manner. Bizon the Champion painted an n × m multiplication table, where the element on the intersection of the i-th row and j-th column equals i·j (the rows and ...
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Let's write all the positive integer numbers one after another from $1$ without any delimiters (i.e. as a single string). It will be the infinite sequence starting with 123456789101112131415161718192021222324252627282930313233343536... Your task is to print the $k$-th digit of this sequence. -----Input----- The fir...
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Welcome to Codeforces Stock Exchange! We're pretty limited now as we currently allow trading on one stock, Codeforces Ltd. We hope you'll still be able to make profit from the market! In the morning, there are $n$ opportunities to buy shares. The $i$-th of them allows to buy as many shares as you want, each at the pri...
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В Берляндском государственном университете локальная сеть между серверами не всегда работает без ошибок. При передаче двух одинаковых сообщений подряд возможна ошибка, в результате которой эти два сообщения сливаются в одно. При таком слиянии конец первого сообщения совмещается с началом второго. Конечно, совмещение мо...
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Daniel is organizing a football tournament. He has come up with the following tournament format: In the first several (possibly zero) stages, while the number of teams is even, they split in pairs and play one game for each pair. At each stage the loser of each pair is eliminated (there are no draws). Such stages are...
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A string a of length m is called antipalindromic iff m is even, and for each i (1 ≤ i ≤ m) a_{i} ≠ a_{m} - i + 1. Ivan has a string s consisting of n lowercase Latin letters; n is even. He wants to form some string t that will be an antipalindromic permutation of s. Also Ivan has denoted the beauty of index i as b_{i}...
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Vanya has a scales for weighing loads and weights of masses w^0, w^1, w^2, ..., w^100 grams where w is some integer not less than 2 (exactly one weight of each nominal value). Vanya wonders whether he can weight an item with mass m using the given weights, if the weights can be put on both pans of the scales. Formally ...
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Jamie is preparing a Codeforces round. He has got an idea for a problem, but does not know how to solve it. Help him write a solution to the following problem: Find k integers such that the sum of two to the power of each number equals to the number n and the largest integer in the answer is as small as possible. As t...
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Mary has just graduated from one well-known University and is now attending celebration party. Students like to dream of a beautiful life, so they used champagne glasses to construct a small pyramid. The height of the pyramid is n. The top level consists of only 1 glass, that stands on 2 glasses on the second level (co...
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After making bad dives into swimming pools, Wilbur wants to build a swimming pool in the shape of a rectangle in his backyard. He has set up coordinate axes, and he wants the sides of the rectangle to be parallel to them. Of course, the area of the rectangle must be positive. Wilbur had all four vertices of the planned...
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Petya has equal wooden bars of length n. He wants to make a frame for two equal doors. Each frame has two vertical (left and right) sides of length a and one top side of length b. A solid (i.e. continuous without breaks) piece of bar is needed for each side. Determine a minimal number of wooden bars which are needed t...
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You have an array a consisting of n integers. Each integer from 1 to n appears exactly once in this array. For some indices i (1 ≤ i ≤ n - 1) it is possible to swap i-th element with (i + 1)-th, for other indices it is not possible. You may perform any number of swapping operations any order. There is no limit on the ...
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A new airplane SuperPuperJet has an infinite number of rows, numbered with positive integers starting with 1 from cockpit to tail. There are six seats in each row, denoted with letters from 'a' to 'f'. Seats 'a', 'b' and 'c' are located to the left of an aisle (if one looks in the direction of the cockpit), while seats...
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After seeing the "ALL YOUR BASE ARE BELONG TO US" meme for the first time, numbers X and Y realised that they have different bases, which complicated their relations. You're given a number X represented in base b_{x} and a number Y represented in base b_{y}. Compare those two numbers. -----Input----- The first line...
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Since most contestants do not read this part, I have to repeat that Bitlandians are quite weird. They have their own jobs, their own working method, their own lives, their own sausages and their own games! Since you are so curious about Bitland, I'll give you the chance of peeking at one of these games. BitLGM and Bi...
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Vova again tries to play some computer card game. The rules of deck creation in this game are simple. Vova is given an existing deck of n cards and a magic number k. The order of the cards in the deck is fixed. Each card has a number written on it; number a_{i} is written on the i-th card in the deck. After receiving...
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One day Kefa found n baloons. For convenience, we denote color of i-th baloon as s_{i} — lowercase letter of the Latin alphabet. Also Kefa has k friends. Friend will be upset, If he get two baloons of the same color. Kefa want to give out all baloons to his friends. Help Kefa to find out, can he give out all his baloon...
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You are given an array of n integer numbers a_0, a_1, ..., a_{n} - 1. Find the distance between two closest (nearest) minimums in it. It is guaranteed that in the array a minimum occurs at least two times. -----Input----- The first line contains positive integer n (2 ≤ n ≤ 10^5) — size of the given array. The second...
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Vector Willman and Array Bolt are the two most famous athletes of Byteforces. They are going to compete in a race with a distance of L meters today. [Image] Willman and Bolt have exactly the same speed, so when they compete the result is always a tie. That is a problem for the organizers because they want a winner....
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Nauuo is a girl who loves writing comments. One day, she posted a comment on Codeforces, wondering whether she would get upvotes or downvotes. It's known that there were $x$ persons who would upvote, $y$ persons who would downvote, and there were also another $z$ persons who would vote, but you don't know whether the...
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Vasya has got a robot which is situated on an infinite Cartesian plane, initially in the cell $(0, 0)$. Robot can perform the following four kinds of operations: U — move from $(x, y)$ to $(x, y + 1)$; D — move from $(x, y)$ to $(x, y - 1)$; L — move from $(x, y)$ to $(x - 1, y)$; R — move from $(x, y)$ to $(x + 1...
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You are given string $s$ of length $n$ consisting of 0-s and 1-s. You build an infinite string $t$ as a concatenation of an infinite number of strings $s$, or $t = ssss \dots$ For example, if $s =$ 10010, then $t =$ 100101001010010... Calculate the number of prefixes of $t$ with balance equal to $x$. The balance of so...
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Polycarp is crazy about round numbers. He especially likes the numbers divisible by 10^{k}. In the given number of n Polycarp wants to remove the least number of digits to get a number that is divisible by 10^{k}. For example, if k = 3, in the number 30020 it is enough to delete a single digit (2). In this case, the r...
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On the Literature lesson Sergei noticed an awful injustice, it seems that some students are asked more often than others. Seating in the class looks like a rectangle, where n rows with m pupils in each. The teacher asks pupils in the following order: at first, she asks all pupils from the first row in the order of t...
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After the big birthday party, Katie still wanted Shiro to have some more fun. Later, she came up with a game called treasure hunt. Of course, she invited her best friends Kuro and Shiro to play with her. The three friends are very smart so they passed all the challenges very quickly and finally reached the destination...
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Mister B once received a gift: it was a book about aliens, which he started read immediately. This book had c pages. At first day Mister B read v_0 pages, but after that he started to speed up. Every day, starting from the second, he read a pages more than on the previous day (at first day he read v_0 pages, at second...
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Dima loves representing an odd number as the sum of multiple primes, and Lisa loves it when there are at most three primes. Help them to represent the given number as the sum of at most than three primes. More formally, you are given an odd numer n. Find a set of numbers p_{i} (1 ≤ i ≤ k), such that 1 ≤ k ≤ 3 p_...
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You are given a description of a depot. It is a rectangular checkered field of n × m size. Each cell in a field can be empty (".") or it can be occupied by a wall ("*"). You have one bomb. If you lay the bomb at the cell (x, y), then after triggering it will wipe out all walls in the row x and all walls in the column...
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Berland Football Cup starts really soon! Commentators from all over the world come to the event. Organizers have already built $n$ commentary boxes. $m$ regional delegations will come to the Cup. Every delegation should get the same number of the commentary boxes. If any box is left unoccupied then the delegations wil...
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You are given sequence a_1, a_2, ..., a_{n} of integer numbers of length n. Your task is to find such subsequence that its sum is odd and maximum among all such subsequences. It's guaranteed that given sequence contains subsequence with odd sum. Subsequence is a sequence that can be derived from another sequence by de...
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The only difference between easy and hard versions is constraints. Polycarp loves to listen to music, so he never leaves the player, even on the way home from the university. Polycarp overcomes the distance from the university to the house in exactly $T$ minutes. In the player, Polycarp stores $n$ songs, each of whic...
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Vivek initially has an empty array $a$ and some integer constant $m$. He performs the following algorithm: Select a random integer $x$ uniformly in range from $1$ to $m$ and append it to the end of $a$. Compute the greatest common divisor of integers in $a$. In case it equals to $1$, break Otherwise, return to ste...
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Today on Informatics class Nastya learned about GCD and LCM (see links below). Nastya is very intelligent, so she solved all the tasks momentarily and now suggests you to solve one of them as well. We define a pair of integers (a, b) good, if GCD(a, b) = x and LCM(a, b) = y, where GCD(a, b) denotes the greatest common...
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Neko loves divisors. During the latest number theory lesson, he got an interesting exercise from his math teacher. Neko has two integers $a$ and $b$. His goal is to find a non-negative integer $k$ such that the least common multiple of $a+k$ and $b+k$ is the smallest possible. If there are multiple optimal integers $k...
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Noora is a student of one famous high school. It's her final year in school — she is going to study in university next year. However, she has to get an «A» graduation certificate in order to apply to a prestigious one. In school, where Noora is studying, teachers are putting down marks to the online class register, wh...
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You are given an array of $n$ integers: $a_1, a_2, \ldots, a_n$. Your task is to find some non-zero integer $d$ ($-10^3 \leq d \leq 10^3$) such that, after each number in the array is divided by $d$, the number of positive numbers that are presented in the array is greater than or equal to half of the array size (i.e.,...
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There are n shovels in Polycarp's shop. The i-th shovel costs i burles, that is, the first shovel costs 1 burle, the second shovel costs 2 burles, the third shovel costs 3 burles, and so on. Polycarps wants to sell shovels in pairs. Visitors are more likely to buy a pair of shovels if their total cost ends with severa...
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Polycarpus likes giving presents to Paraskevi. He has bought two chocolate bars, each of them has the shape of a segmented rectangle. The first bar is a_1 × b_1 segments large and the second one is a_2 × b_2 segments large. Polycarpus wants to give Paraskevi one of the bars at the lunch break and eat the other one him...
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Polycarp and Vasiliy love simple logical games. Today they play a game with infinite chessboard and one pawn for each player. Polycarp and Vasiliy move in turns, Polycarp starts. In each turn Polycarp can move his pawn from cell (x, y) to (x - 1, y) or (x, y - 1). Vasiliy can move his pawn from (x, y) to one of cells: ...
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Petr wants to make a calendar for current month. For this purpose he draws a table in which columns correspond to weeks (a week is seven consequent days from Monday to Sunday), rows correspond to weekdays, and cells contain dates. For example, a calendar for January 2017 should look like on the picture: $\left. \begin{...
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The year 2015 is almost over. Limak is a little polar bear. He has recently learnt about the binary system. He noticed that the passing year has exactly one zero in its representation in the binary system — 2015_10 = 11111011111_2. Note that he doesn't care about the number of zeros in the decimal representation. Lim...
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You are given an integer N. Consider all possible segments on the coordinate axis with endpoints at integer points with coordinates between 0 and N, inclusive; there will be $\frac{n(n + 1)}{2}$ of them. You want to draw these segments in several layers so that in each layer the segments don't overlap (they might touc...
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Anya loves to fold and stick. Today she decided to do just that. Anya has n cubes lying in a line and numbered from 1 to n from left to right, with natural numbers written on them. She also has k stickers with exclamation marks. We know that the number of stickers does not exceed the number of cubes. Anya can stick a...
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Suppose you are performing the following algorithm. There is an array $v_1, v_2, \dots, v_n$ filled with zeroes at start. The following operation is applied to the array several times — at $i$-th step ($0$-indexed) you can: either choose position $pos$ ($1 \le pos \le n$) and increase $v_{pos}$ by $k^i$; or not choo...
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Let's denote d(n) as the number of divisors of a positive integer n. You are given three integers a, b and c. Your task is to calculate the following sum: $\sum_{i = 1}^{a} \sum_{j = 1}^{b} \sum_{k = 1}^{c} d(i \cdot j \cdot k)$ Find the sum modulo 1073741824 (2^30). -----Input----- The first line contains three s...
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Bessie the cow and her best friend Elsie each received a sliding puzzle on Pi Day. Their puzzles consist of a 2 × 2 grid and three tiles labeled 'A', 'B', and 'C'. The three tiles sit on top of the grid, leaving one grid cell empty. To make a move, Bessie or Elsie can slide a tile adjacent to the empty cell into the em...
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Alexander is learning how to convert numbers from the decimal system to any other, however, he doesn't know English letters, so he writes any number only as a decimal number, it means that instead of the letter A he will write the number 10. Thus, by converting the number 475 from decimal to hexadecimal system, he gets...
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Array of integers is unimodal, if: it is strictly increasing in the beginning; after that it is constant; after that it is strictly decreasing. The first block (increasing) and the last block (decreasing) may be absent. It is allowed that both of this blocks are absent. For example, the following three arrays a...
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At first, let's define function $f(x)$ as follows: $$ \begin{matrix} f(x) & = & \left\{ \begin{matrix} \frac{x}{2} & \mbox{if } x \text{ is even} \\ x - 1 & \mbox{otherwise } \end{matrix} \right. \end{matrix} $$ We can see that if we choose some value $v$ and will apply function $f$ to it, then apply $f$ to $f(v)$, an...
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Consider a billiard table of rectangular size $n \times m$ with four pockets. Let's introduce a coordinate system with the origin at the lower left corner (see the picture). [Image] There is one ball at the point $(x, y)$ currently. Max comes to the table and strikes the ball. The ball starts moving along a line tha...
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Gerald bought two very rare paintings at the Sotheby's auction and he now wants to hang them on the wall. For that he bought a special board to attach it to the wall and place the paintings on the board. The board has shape of an a_1 × b_1 rectangle, the paintings have shape of a a_2 × b_2 and a_3 × b_3 rectangles. Si...
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Masha really loves algebra. On the last lesson, her strict teacher Dvastan gave she new exercise. You are given geometric progression b defined by two integers b_1 and q. Remind that a geometric progression is a sequence of integers b_1, b_2, b_3, ..., where for each i > 1 the respective term satisfies the condition b...