Compilare: user.cpp:32:6: warning: ISO C++ forbids declaration of ‘main’ with no type [-Wreturn-type] main() ^ user.cpp: In function ‘int main()’: user.cpp:34:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("prefix2.in", "r", stdin); ^ user.cpp:35:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("prefix2.out", "w", stdout); ^