When I submit my code here for Problem C to Codeforces Round 291, it gives me runtime error although I've tried my code both on my local compiler and on ideone.com, both of which give me correct outputs. Why is this happening? Any help would be appreciated.

Most of the codeforces/topcoder contest times are too early for me on the West coast of the US, because I have to go to school. Is there any websites that are like codeforces(ie such as Topcoder, but geared more towards American times) that hosts contests in times that are more comfortable for USA times?