Compilare: user.c: In function ‘main’: user.c:153:11: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen ("hashuri.in", "r", stdin); ^ user.c:154:11: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen ("hashuri.out", "w", stdout); ^ user.c:157:9: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d", &n); ^ user.c:162:11: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d%d", &op, &val); ^