The function pow in C++ is only defined for floating point numbers. So pow(10, 2) might return 99.99999999999 instead of 100 (e.g. when performed on a different compiler / different architecture) and then get truncated to 99 when you convert it to an int. If you want to perform integer exponentiation, always write a pow function yourself.

I also had problem with pow in this problem at the contest, so I changed it to my own binary power function, it worked. Don't use pow, it is slow and it have problems with long long.

Here is your fixed submission: http://codeforces.com/contest/808/submission/28207320