#include <iostream>
#include <algorithm>
#include <numeric>
#include <vector>
#include <functional>
constexpr int ONE = true;
constexpr int TWO = std::plus<int>{}(ONE,ONE);
constexpr int ZERO = std::minus<int>{}(ONE,ONE);
int main()
{
    int N;std::cin>>N;
    if(N==ONE){
        std::cout << "NO"<<std::endl;
        return ZERO;
    }
    for(int p = TWO; std::multiplies<int>{}(p,p)<=N;p=std::plus<int>{}(p,ONE)){
        if(N%p==ZERO){ 
            std::cout << "NO"<<std::endl;
            return ZERO;
        }
    }
    std::cout << "YES"<<std::endl;
    return ZERO;
}