Compilare: user.c:33:1: warning: return type defaults to ‘int’ [enabled by default] main() { ^ user.c: In function ‘main’: user.c:34:9: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("fact.in", "r", stdin); ^ user.c:35:9: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("fact.out", "w", stdout); ^ user.c:40:7: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &p); ^