Compilare: main.cpp: In function 'void input::setupIO(const string&)': main.cpp:85:60: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen((PROB + ".in").c_str(), "r", stdin); ^ main.cpp:86:62: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen((PROB + ".out").c_str(), "w", stdout); ^ main.cpp: In member function 'char InParser::read_ch()': main.cpp:173:38: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fread(buff, 1, 4096, fin); ^