#include<iostream.h>
#include<math.h>
void main(){
	int m,i;
	float k;
	cout<<"輸入整數"<<endl;
	cin>>m;
	if(m==2)cout<<m<<"是素數"<<endl;
	else{
		k=sqrt(m);
		for(i=2;i<=k;i++)if(m%i==0)break;
		if(i>k)cout<<m<<"是素數"<<endl;
		else cout<<m<<"不是素數"<<endl;
	}
}