#include <stdio.h>
#include <iostream>
using namespace std;

int main()
{
	int x, y, n;
	float r;
	while( 1 )
	{
		scanf("%d %d %d %f", & x, &y, &n, &r);
		if( !x && !y && !n && !r )
			break;
		
		double Debth = (double) x;
		for( int i = 0 ; i < 12*n ; i++ )
		{
			Debth += Debth * r / 1200;
			Debth -= y;
		}
		if( Debth <= 0 )
			printf("YES\n");
		else
			printf("NO\n");
	}
	return 0;
}