using System;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static void Main(string[] args)
    {
        long[] ary = Console.ReadLine().Split().Select(long.Parse).ToArray();
        long h = ary[0];
        long w = ary[1];
        long n = ary[2];
        long k = ary[3];
        string ans = "NO";

        long all = h * w;

        if (all - n <= 0)
        {
            if (all == k)
            {
                ans = "YES";
            }
        }
        else
        {
            if (all % n == n % k)
            {
                ans = "YES";
            }
        }

        Console.WriteLine(ans);
        Console.Read();
    }
}