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| 11332 | |
| Summing Digits | |
| For a positive integer n, let f(n) denote the sum | |
| of the digits of n when represented in base 10. | |
| It is easy to see that the sequence of numbers | |
| n, f(n), f(f(n)), f(f(f(n))), . . . eventually becomes a | |
| single digit number that repeats forever. Let this sin- | |
| gle digit be denoted g(n). | |
| For example, consider n = 1234567892. Then: | |
| f(n) = 1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 2 = 47 | |
| f(f(n)) = 4 + 7 = 11 | |
| f(f(f(n))) = 1 + 1 = 2 | |
| Therefore, g(1234567892) = 2. | |
| Input | |
| Each line of input contains a single positive integer n | |
| at most 2,000,000,000. Input is terminated by n = 0 | |
| which should not be processed. | |
| Output | |
| For each such integer, you are to output a single line | |
| containing g(n). | |
| Sample Input | |
| 2 | |
| 11 | |
| 47 | |
| 1234567892 | |
| 0 | |
| Sample Output | |
| 2 | |
| 2 | |
| 2 | |
| 2 |