#include<stdio.h>
int main(){
  int a,b,c,d;
  scanf("%d %d %d %d",&a,&b,&c,&d);
  while(a > 0 && c > 0){
    if(0 >= (a = a - d)){
    	printf("No\n",a);
    }
  	if(0 >= (c = c - b)){
    	printf("Yes\n");
    }
  }
  return 0;    
}