#include <bits/stdc++.h>
using namespace std;

int main() {
  long L, R, M, K;
  cin >> L >> R >> M >> K;
  if (!K || !L) return cout << "Yes" << "\n", 0;
  long mi = L * K - 1;
  long mx = R * K;
  cout << ((mx / M - mi / M) ? "Yes" : "No") << "\n";
}