#include <iostream>
using namespace std;

int main()
{
    long long x,y,n;
    double r;

    //cout.precision(20);
    //cout << double(1000000000)+0.1;

    cin >> x >> y >> n >> r;
    long long cela;
    double desatinna;

    while(x!=0 or y!=0 or n!=0 or r!=0)
    {
        bool urobilo = false;
        long long pom;

        for(int i=1;i<=n*12;i++)
        {

            double konst = (r +1200) / double(1200);

            pom = (x+desatinna)*konst - y;
            desatinna = (x+desatinna)*konst - y - pom;

            if(x<(pom+desatinna)){
                cout << "NO" << endl;
                urobilo=true;
                break;
                }

            if(x<0)
            {
                cout << "YES" << endl;
                urobilo=true;
                break;
            }

            x=pom;

            //cout << "krok " << i << " pom je " << pom << endl;
        }

        //cout << "krok koniec pom je " << pom << endl;

        if(not urobilo) cout << "NO" << endl;

        cin >> x >> y >> n >> r;
    }

    return 0;
}