Compilare: user.cpp: In function ‘int main()’: user.cpp:80:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("piese3.in", "r", stdin); ^ user.cpp:81:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("piese3.out", "w", stdout); ^ user.cpp: In member function ‘void FastReader::AdvancePointer()’: user.cpp:63:50: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buffer_, 1, kMaxDim, stdin); ^