#include<stdio.h>
int main()
{
int a,m=2,n=1;
for(;;)
{
m=2;
n=1;
printf("Please enter your number");
scanf("%d",&a);
do
{
if(a%m==0)
n=0;
m++;
}
while(m!=a);
if(n==0)
printf("NO\n");
else
printf("YES\n");
}
}