#include<bits/stdc++.h>
using namespace std;
long long n;
bool Judge(long long num){
    if(num<=1)return 0;
    for(long long i=2;i*i<=num;i++)if(num%i==0)return 1;
    return 0;
}
int main(){
    cin>>n;
    if(n==1){
        cout<<"NO"; return 0;
    }
    int s=sqrt(n);
    if(s*s==n&&!Judge(s)){
        cout<<"NO"; return 0;
    }
    cout<<(Judge(n)?"YES\n":"NO\n");
}