You are using long int which has different meanings on different plataforms, on windows it means a 32 int integer, while on linux it means a 64 bit integer.

When you are using a linux based plataform, as Ideone does, and I guess you too, you get the right answer, as if you were using a Windows plataform you would get the wrong answer.

Codeforces runs on a Windows machine and that's why you are getting Wrong Answer here.

My suggestion is that you should never use long int and always use either long long or int.

More information about it here: https://en.wikipedia.org/wiki/64-bit_computing#64-bit_data_models