For 64-bit integers, both long long int and __int64 is supported and they are equivalent. But only "%I64d" is supported when reading with scanf or writing with printf. "%lld" is not supported because GCC and G++ from MinGW use msvcrt.dll which does not support the C99 standard.

(G++ only) As required by the ISO C++ standard, the return type of the main function must be int, otherwise it will cause Compile Error.