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

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

	long long x = ( (H*W)%N );
	if(x==0) x += N;

	if(x == K){
		cout << "YES" << endl;
	}else{
		cout << "NO" << endl;
	}
	return 0;
}