i had runtime error in this submission and i was going crazy finding where the error is

after 2 hours of debugging and tracing .. i didn't find the problem .. i did something stupid and the problem got accepted .. i don't know why actually ...

does any one knows where was the error in the first code ? ?

and why C++ behaves like that

run time error : http://mirror.codeforces.com/contest/706/submission/20629423

accepted :http://mirror.codeforces.com/contest/706/submission/20629645