Compilare: user.cpp: In function ‘int main()’: user.cpp:100:19: warning: unused variable ‘k’ [-Wunused-variable] for(int i = 1, k = 0; i <= N; i++) { ^ user.cpp: In constructor ‘InputReader::InputReader(const char*)’: user.cpp:25:44: 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:47:50: 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); ^