#include
#include
int prime(int m)
{
int i,n;
if(m==1)return 0;
n=(int)sqrt((double)m);
for(i=2;i<=n;i++)
if(m%i==0)return 0;
return 1;
}
void main()
{
int n;
scanf("%d",&n);
if(prime(n))
printf("%d is a prime.\n",n);
else
printf("%d is not a prime.\n",n);
}