#include <stdio.h>

int main(){
  
  int a,b,c,d;
  int takahashi = 100;
  int aoki = 100;
  int flag1, flag2;
  
  scanf("%d %d %d %d", &a, &b, &c, &d);
  
  while(takahashi <= 0){
  takahashi = a - d;
  	flag1++;
  }
  
  while(aoki <= 0){
  aoki = c - b;
  	flag2++;
  }
  
  if(flag1 <= flag2){
  	printf("Yes");
  }else{
  	printf("No");
  }
  
  return 0;
}