#include <bits/stdc++.h>
using namespace std;
using ll = long long;
constexpr long long MOD = 1000000007;
int main(){
    ll l, r, m, k;
    ll mini = 1e12;
    ll maxi = 0;
    cin >> l >> r >> m >> k;
    if (k == 0) cout << "Yes" << endl;
    else if(k*l==0){
        if (-1 != k * r / m) cout << "Yes" << endl;
        else
            cout << "No" << endl;}
    else {
        if ((k * l-1) / m != k * r / m) cout << "Yes" << endl;
        else
            cout << "No" << endl;
    }
}