Compilare: user.cpp: In function ‘int main()’: user.cpp:81:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("alpin.out","w",stdout); ^ user.cpp: In constructor ‘InputReader::InputReader(const char*)’: user.cpp:23:33: 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, SZ, in); ^ user.cpp: In member function ‘void InputReader::advance()’: user.cpp:50:37: 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, SZ, in); ^