//Haha TTpro
//BCPRIME
//http://www.spoj.com/PTIT/problems/BCPRIME/
#include <iostream>

using namespace std;

bool HahaTTproUltimate(int kaboom);

int main()
{
    long int hahattpro;
    cin >>hahattpro;
    if (HahaTTproUltimate(hahattpro)) cout <<"YES"; else cout<<"NO";
}

bool HahaTTproUltimate(int kaboom)
{
        int fuck;
        if (kaboom == 1) return false;
        for (fuck = 2; fuck< kaboom; fuck ++ )
        {
            if ((kaboom % fuck) == 0) return false;
        }

        return true;

}