Compilare: user.c: In function ‘Build’: user.c:38:10: warning: variable ‘cn’ set but not used [-Wunused-but-set-variable] node_t *cn; ^ user.c: In function ‘main’: user.c:67:9: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("metrou2.in", "r", stdin); ^ user.c:68:9: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("metrou2.out", "w", stdout); ^ user.c:69:7: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%i%i", &n, &m); ^ user.c:71:8: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%i", &p[i]); ^ user.c:74:8: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%i%i", &a, &b); ^