#include<bits/stdc++.h>

using namespace std;
using ll = long long;


int main()
{
    ll L, R, M, K;
    cin >> L >> R >> M >> K;
    ll fL = L * K, fR = R * K;
    if(K == 0 || L == 0) {
        cout << "Yes" << endl;
        return 0;
    }
    cout << ((fR / M) - ((fL - 1) / M) ? "Yes" : "No") << endl;
}