Compilare: user.c: In function ‘main’: user.c:27:8: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen(filein, "r", stdin); ^ user.c:28:6: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%ld %ld", &M, &N); ^ user.c:80:8: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen(fileout, "w", stdout); ^