Compilare: main.cpp: In function 'int main()': main.cpp:126:13: warning: unused variable 'val' [-Wunused-variable] int val, type, a, b ; ^~~ main.cpp: In member function 'void InputReader::advance()': main.cpp:16:61: 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) ; ^ main.cpp: In constructor 'InputReader::InputReader(const char*)': main.cpp:24:53: 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) ; ^