Compilare: user.cpp: In function ‘int solve(int, int)’: user.cpp:47:47: warning: variable ‘val2’ set but not used [-Wunused-but-set-variable] int answer = 0, nr1, nr2, nr3, nr4, val1, val2; ^ user.cpp: In member function ‘void input_reader::advance()’: user.cpp:17:53: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread( buffer, SIZE, 1, input_file ); ^ user.cpp: In constructor ‘input_reader::input_reader(const char*, const char*)’: user.cpp:27:49: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread( buffer, SIZE, 1, input_file ); ^