// I SELL YOU...! 
#include<iostream>
#include<vector>
#include<algorithm>
#include<functional>
#include<queue>
#include<chrono>
#include<iomanip>
#include<map>
#include<set>
using namespace std;
using ll = long long;
using P = pair<ll,ll>;
using TP = tuple<ll,ll,ll>;
void init_io(){
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(18);
}
signed main(){
  init_io();
  ll l,r,m,k,le,ri;
  cin >> l >> r >> m >> k;
  le = l*k;
  ri = r*k;
  if(le%m==0||ri%m==0||le/m!=ri/m){
    cout <<"Yes\n";
  }else{
    cout <<"No\n";
  }
}