#include <bits/stdc++.h>
#define PI 3.14159265359
using namespace std;
const int64_t MOD = 1e9 + 7;

int main() {
	int64_t H, W, N, K;
	cin >> H >> W >> N >> K;

	int64_t a = H * W;
	a %= N;
	if (!a) a = N;

	if (a == K) {
		cout << "YES" << endl;
	}
	else {
		cout << "NO" << endl;
	}
}