#include<iostream>
#include<functional>

using namespace std;

int zero, base;

bool sosu(int idx)
{
  ++base;
  ++base;
  if(idx < base) return (false);
  for(; multiplies< int >{}(base, base) <= idx; base++) {
    if(idx % base == zero) return (false);
  }
  return (true);
}

int main()
{
  int idx;
  cin >> idx;
  cout << (sosu(idx) ? "YES" : "NO") << endl;
}