#include <iostream>
using namespace std;
int main(){
	long long int h,w,n,k,s;
	cin>>h>>w>>n>>k;
	s=(h*w)%n;
	if(s==0)	s+=n;
	if(s==k)	cout<<"YES"<<endl;
	else	cout<<"NO"<<endl;
	return 0;
}