| As an experienced boomerangist, you take great pride in your trusty boomerang, | |
| and you'd like to be able to show it off! Unfortunately, it doesn't look quite | |
| right yet... | |
| Like all boomerangs, yours is symmetrical in shape, with two **N** millimetre- | |
| long halves. However, what's not necessarily symmetrical is its paint job — | |
| each millimetre-long section of each half has been painted some color. There | |
| are 26 possible colors, represented by uppercase letters ("A" to "Z"), and the | |
| **i**th section of the left half (counting from the left end) has color | |
| **Ai**, while the **i**th section of the right half (counting from the right | |
| end) has color **Bi**. You'd like your boomerang to be completely symmetrical | |
| (which is the case when the **i**th section in the left half has the same | |
| color as the **i**th section in the right half, for all 1 ≤ **i** ≤ **N**) as | |
| soon as possible! | |
| To that end, you're enlisting the help of your two best friends, Jack and | |
| Jill, to repaint the left half of your boomerang until it matches the right | |
| half. Every second, Jack may paint over a "prefix" of the left half with a | |
| solid color, while Jill may simultaneously paint over a disjoint "suffix". In | |
| other words, every second, Jack and Jill will each select a color (from "A" to | |
| "Z"), Jack will select a value **x** (0 ≤ **x** ≤ **N**), and Jill will select | |
| a value **y** (0 ≤ **y** ≤ **N - x**). Then, Jack will repaint the first **x** | |
| sections of the left half of the boomerang with his color, while Jill will | |
| repaint the last **y** sections of the left half of the boomerang with her | |
| color. Painting over a section completely overwrites its previous color. | |
| What's the minimum amount of time (in seconds) it can take Jack and Jill to | |
| make your boomerang completely symmetrical? | |
| ### Input | |
| Input begins with an integer **T**, the number of boomerangs you want to | |
| decorate. For each boomerang, there is first a line containing the integer | |
| **N**, then two lines that each contain a string of length **N**. The **i**th | |
| character of the second line is **Ai**. The **i**th character of the third | |
| line is **Bi**. | |
| ### Output | |
| For the **i**th boomerang, print a line containing "Case #**i**: " followed by | |
| the minimum number of seconds it will take Jack and Jill to make your | |
| boomerang's paint job symmetrical. | |
| ### Constraints | |
| 1 ≤ **T** ≤ 75 | |
| 1 ≤ **N** ≤ 100,000 | |
| ### Explanation of Sample | |
| The first boomerang is already symmetrical, so no work needs to be done. The | |
| second boomerang can be made symmetrical in 1 second. Jack will cover the | |
| first millimetre with 'C', and Jill will cover the third millimetre with 'A'. | |
| The third boomerang takes 2 seconds to paint. One possible solution is for | |
| Jack to paint the first two millimetres with 'A' and then the first millimetre | |
| with 'B'. | |