Compilare: user.c: In function ‘main’: user.c:136:11: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen ("hotel.in", "r", stdin); ^ user.c:137:11: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen ("hotel.out", "w", stdout); ^ user.c:139:9: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d %d\n", &n, &m); ^ user.c:157:11: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d", &op); ^ user.c:161:13: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d %d", &left, &add); ^ user.c:168:13: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d %d", &left, &add); ^