#include<stdio.h>

int main()
{
	int A,B,C,D;
	while(scanf("%d %d %d %d",&A,&B,&C,&D)!=EOF)
	while(A>0 && C>0)
	{
		C=C-B;
		A=A-D;
		if(C==0)
		printf("Yes\n");
		if(A==0)
		printf("No\n");
	}	
	return 0;
 } 