#include <bits/stdc++.h>
using namespace std;
int main(){
  int th, ta, ah, aa;
  cin >> th, ta, ah, aa;
  bool x = false;
  while( x ){
    ah - ta;
    if(ah - ta <= 0){
      x = true;
      cout << "Yes" << endl;
      break;
    }
    th - aa;
    if(th - aa <= 0){
      x = true;
      cout << "No" << endl;
      break;
    }
  }
}
