#include <stdio.h>




int main(){
    int Y,N,date, maxN;
    double X,r,helpingOne;

    
    
    while (1){
        scanf("%lf %d %d %lf",&X, &Y, &N, &r);
        if (X==0 && Y==0 && r==0 && N==0)
            break;
        date = 1;
        r/=1200;
        maxN=12*N;
        helpingOne=X;
        while (1){
            X+=X*r-Y;
            if (X>helpingOne){printf("NO\n");break;};
            if(X<=0){printf("YES\n");break;}
            if (date>=maxN){printf("NO\n");break;}
            date++;
        
        }
    
    }

return 0;
}