#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <cstdio>
#include <cstring>
#include <cmath>
using namespace std;
using ll = long long;

bool solve() {
    ll l, r, m, k;
    cin >> l >> r >> m >> k;

    if (r + 1 - l >= m || l % m > r % m || l % m == 0) return true;

    l *= k;
    r *= k;

    if (r + 1 - l >= m || l % m > r % m || l % m == 0) return true;

    return false;
}

int main() {
    cout << (solve() ? "Yes" : "No") << endl;

    return 0;
}