Compilare: user.c: In function ‘main’: user.c:23:11: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen ("disjoint.in", "r", stdin); ^ user.c:24:11: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen ("disjoint.out", "w", stdout); ^ user.c:27:9: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d%d", &n, &m); ^ user.c:36:18: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] int t; scanf ("%d", &t); ^ user.c:37:21: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] int a, b; scanf ("%d%d", &a, &b); ^