Compilare: user.cpp: In function ‘int main()’: user.cpp:124:79: warning: operation on ‘updates_and_undos’ may be undefined [-Wsequence-point] version[++ updates_and_undos] = version[updates_and_undos - x - 1]; ^ user.cpp: In constructor ‘InputReader::InputReader(const char*)’: user.cpp:14:47: 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:36:51: 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); ^