#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main(int argc, char** argv){
	double x,y,n,r,debt;
	while(1){
		scanf("%lf %lf %lf %lf", &x, &y, &n, &r);
		if(x==0 && y==0 && n==0 && r==0){
			break;
		}
		n *= 12;
		debt = x*pow((1+(r/1200)),n) - n*y;
		if(debt<= 0)
			printf("YES\n");
		else
			printf("NO\n");
	}
	return 0;
}