#include <bits/stdc++.h>
using namespace std;

main()
{
    while (true)
    {
        int n, count = 0;
        cin >> n;

        if (n == 0)
        {
            break;
        }
        else
        {
            for (int i = 1; i <= n; i++)
            {
                if(n%i==0)
                {
                    count++;
                }
            }

            if(count%2==0)
            {
                cout<<"NO"<<endl;
            }
            else
            {
                cout<<"YES"<<endl;
            }
        }
    }
}