//
// File:   main.cc
// Author: cteam007
//
// Created on October 22, 2011, 3:45 PM
//

//#include <stdlib.h>

#include <iostream>
using namespace std;

//
//
//
int main(int argc, char** argv) {
    double  R=0;
    int  X=0, Y=0, N=0,i;
    bool A=false;
    while(1)
    {scanf("%d %d %d %lf", &X, &Y, &N, &R);
     i=0;
     if(X==0&&Y==0&&N==0&&R==0)return 0;
     if(X/Y>N*12)i=N*12;
     if(R/1200*X>Y)i=N*12;
     if(R==0){if(X/Y<=N*12){A=true;i=N*12;}else{i=N*12;}}
     
     
     for(i=i;i<N*12;i++) {
         X=X*(R/1200+1);
         X=X-Y;
         if(X<=0){A=true;break;}
     }
     
     if(A==false)printf("NO\n");
     else{printf("YES\n");}
     A=false;
    }
    return 0;
}