#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef vector<int> vi;
typedef pair<int, int> pii;
#define pb push_back
#define mp make_pair
#define fi first
#define se second

int main()
{
	ll h,w,a,b;
	cin>>h>>w>>a>>b;
	h*=w;
	if(h%a==0&&a==b)cout<<"YES"<<endl;
	else if(h%a&&h%a==b)cout<<"YES"<<endl;
	else cout<<"NO"<<endl;
	return 0;
}