#include <bits/stdc++.h>
using namespace std;

int main() {
	long long l, r, m, k;
	cin >> l >> r >> m >> k;
	
	long long low = l * k, high = r * k;
	long long ans = (high / m) - ((low - 1) / m);
	
	cout << ((ans > 0 or k == 0) ? "Yes" : "No") << '\n';
	
	return 0;
}