#include <iostream>
using namespace std;
int main()
{
    long a, c = 0;
    cin >> a;
    for (int i = 2; i <= a - 1; i++)
    {
        if (a % i != 0)
        {
            c++;
        }
    }
    if (c == a - 2)
    {
        cout << "YES";
    }
    else
        cout << "NO";
    return 0;
}