#include<bits/stdc++.h>

using namespace std;
using ll = long long int;
using lc = complex<double>;

int main(void) {
    constexpr ll MOD = 1e9 + 7;
    constexpr double PI = acos(-1);
    cout << fixed << setprecision(32);
    cin.tie(0); ios::sync_with_stdio(false);

    ll l, r, m, k;
    cin >> l >> r >> m >> k;
    ll a = l*k, b = r*k;
    cout << (a/m != b/m || a%m == 0 ? "Yes" : "No" ) << endl;
}