If you have WA, you must use long long(or int64 in Pascal).And don't use sum/3>n,use sum>n*3.After that you have AC.
По русски.
Не используйте типы int(или integer). Используйте типы int64(или long long). При сравнение не сумма/3>выхода,а сумма>выход*3. Желаю всем красивых AC!

P.S. Sorry for bad English.

thx

Well, this method guarantee you simple AC solution, but to decrease time and get finally 0.015 secs you should come back to 32-bit ints. Keep somewhere the undivided part (the remainder) and try to eliminate it with each new value read. At the time you compare the sum to N (or the remains of N to zero) you should not forget the remainder. Write something as "if(n<0||!n&&r)" in the place of condition.

Thanks helped very much!!!!