#include <iostream>
#include <math>

using namespace std;

int main()
{
cout <<"Enter a number:";
int num;
boolean isPrime = true;
cin >>;
for (int i = 2; i <= sqrt(num); i++)
{
if (num % i == 0) 
{
isPrime = false;
break;
}
if (isPrime)
cout <<"YES"<<endl;
else
cout <<"NO<<endl;
return 0;
}