#include <bits/stdc++.h>

using namespace std;

#define REP(i,n) for(int i=0; i<(int)(n); i++)

int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);

  long long l, r, m, k;
  cin >> l >> r >> m >> k;

  l *= k;
  r *= k;

  bool ck = false;
  for (long long x = l/m * m; x <= r; x += m) {
    if (x >= l && x % m == 0) {
      ck = true;
      break;
    }
  }

  if (ck)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
  
  return 0;
}