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