Compilare: user.c: In function ‘main’: user.c:25:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("rucsac.in", "r", stdin); ^ user.c:26:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("rucsac.out", "w", stdout); ^ user.c:27:10: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &N, &G); ^ user.c:29:14: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &W[i], &P[i]); ^