#include <stdio.h>

double cap, pay, rate;
int years;

int main() {
	while (42) {
		scanf("%lf %lf %d %lf\n", &cap, &pay, &years, &rate);
		if (cap == 0)
			break;
		
		int months = years * 12;
		double mrate = 1.0 + rate / 1200.0;
		
		int i;
		for (i = 1; i <= months; ++i) {
			cap *= mrate;
			cap -= pay;
			if (cap <= 0) {
				printf("YES\n");
				goto paid;
			}
		}
		printf("NO\n");
	paid: ;
	}
	return 0;
}