Compilare: user.c:2:19: warning: return type defaults to ‘int’ [enabled by default] long long p,k,i,n;main(){freopen("fact.in","r",stdin);freopen("fact.out","w",stdout); ^ user.c: In function ‘main’: user.c:2:33: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] long long p,k,i,n;main(){freopen("fact.in","r",stdin);freopen("fact.out","w",stdout); ^ user.c:2:62: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] long long p,k,i,n;main(){freopen("fact.in","r",stdin);freopen("fact.out","w",stdout); ^ user.c:3:6: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%lld",&p);for(n=2;p>k;n++)for(i=5,k=0;i<=n;i*=5)k+=n/i;printf("%lld",n-1);} ^