#include <iostream>
#include <vector>
#include<map>
#include<string>
#include<algorithm>
#include<sstream>
#include<cmath>
using namespace std;


int main() {
	int l,r,m,k;
	cin >> l>>r>>m>>k;
	int n=0;
	int count=0;
	bool flag = false;
	vector<int> k_div;
	if (k != 0) {
		for (int i = 1; i <= sqrt(k); i++) {
			if (k % i == 0)k_div.push_back(i);
		}
		k_div.push_back(k);
		for (auto it = k_div.begin(); it != k_div.end(); it++) {
				if ((r - l) * (*it) >= m) {
					flag = true;
					break;
				}

		}
	}
	else flag = true;
	
	if (flag) {
		cout << "Yes";
	}
	else {
		cout << "No";
	}
}