# include <iostream.h>
void main()
{
int x;
cout<<"please input x:\n";
cin>>x;
if(x==1) cout<<"1是素数";
else
{
for( int i=2;i<x;i++)
if(x%i==0) break;
if(x==i) cout<<x<<"是素数";
else cout<<x<<"不是素数";}
}//