Compilare: user.c: In function ‘main’: user.c:43:9: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("disjoint.in", "r", stdin); ^ user.c:44:9: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("disjoint.out", "w", stdout); ^ user.c:50:7: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &N, &M); ^ user.c:59:8: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d", &operation, &x, &y); ^