Compilare: user.c: In function ‘main’: user.c:60:9: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("abcacm.in", "r", stdin); ^ user.c:61:9: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("abcacm.out", "w", stdout); ^ user.c:63:7: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &t); ^ user.c:65:8: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d %d", &a, &b, &c, &i); ^