#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i = 0; i < (n);i++)
#define sz(x) int(x.size())
typedef long long ll;
typedef pair<int,int> P;
constexpr int INF = 2e9;

int main() {
  int l, r, m, k;
  cin >> l >> r >> m >> k;
  if (k == 0 || l == 0) {
    cout << "Yes" << endl;
    return 0;
  }
  if (l <= m && m <= r) {
    cout << "Yes" << endl;
    return 0;
  }
  if (l <= m/k && m/k <= r) {
    cout << "Yes" << endl;
    return 0;
  }
  if (l <= m * k && m * k <= r) {
    cout << "Yes" << endl;
  }
  cout << "No" << endl;
  return 0;
}