using System;

class S27_massgame{
  public static int Main(string[] args){
    int w,h;
    long n,k, end;

    w = int.Parse(Console.ReadLine());
    h = int.Parse(Console.ReadLine());
    n = long.Parse(Console.ReadLine());
    k = long.Parse(Console.ReadLine());

    end = w * h % n;
    if(end == 0) end = n;
    if(k == end){
      Console.WriteLine("YES");
    }else{
      Console.WriteLine("NO");
    }

    return 0;
  }
}