Compilare: user.c: In function ‘main’: user.c:53:11: warning: unused variable ‘fo’ [-Wunused-variable] FILE *fo = freopen("rest.out", "w", stdout); ^ user.c:52:11: warning: unused variable ‘fi’ [-Wunused-variable] FILE *fi = freopen("rest.in", "r", stdin); ^ user.c:54:10: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d", &N, &B, &P); ^ user.c:56:14: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &t); ^ user.c:59:10: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &M); ^ user.c:61:14: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d", &op, &k, &l); ^ user.c: In function ‘concat’: user.c:19:12: warning: ‘r’ may be used uninitialized in this function [-Wmaybe-uninitialized] k = (a * r + b) % P; ^