#ifndef LOCAL
#include <bits/stdc++.h>

using namespace std;

#define debug(...) (void(0))
#else
#include "algo/debug.h"
#endif

void solve() {
    int L, R, M, K;
    cin >> L >> R >> M >> K;
    if (K == 0) {
        cout << "Yes\n";
        return;
    }
    if (R - L + 1 >= M) {
        cout << "Yes\n";
    } else {
        int lr = L % M;
        int rr = R % M;
        int64_t mn = min(lr, rr), mx = max(lr, rr);
        int64_t hi = mx * K, lo = mn * K;
        int64_t cnt = hi / M - max(0L, lo - 1) / M;
        cout << (cnt ? "Yes\n" : "No\n");
    }
}

int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    int tt = 1;
    // std::cin >> tt;
    while (tt--) {
        solve();
    }
}