Compilare: user.cpp: In function ‘int main()’: user.cpp:304:11: warning: variable ‘fin’ set but not used [-Wunused-but-set-variable] FILE *fin, *fout; ^ user.cpp:304:17: warning: variable ‘fout’ set but not used [-Wunused-but-set-variable] FILE *fin, *fout; ^ user.cpp:309:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &M, &N); ^