Compilare: user.cpp: In constructor ‘InputReader::InputReader(const char*)’: user.cpp:18:47: 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 member function ‘void InputReader::advance()’: user.cpp:40:51: 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 function ‘int main()’: user.cpp:179:68: warning: ‘y’ may be used uninitialized in this function [-Wmaybe-uninitialized] cout << x - 1 << ' ' << y - 1 << ' ' << x - 1 + dx << ' ' << y - 1 + dy << '\n'; ^ user.cpp:179:47: warning: ‘x’ may be used uninitialized in this function [-Wmaybe-uninitialized] cout << x - 1 << ' ' << y - 1 << ' ' << x - 1 + dx << ' ' << y - 1 + dy << '\n'; ^