using System;

public class Hello
{
    public static void Main()
    {
        string[] line = Console.ReadLine().Trim().Split(' ');
        var h = long.Parse(line[0]);
        var w = long.Parse(line[1]);
        var hw = h * w;
        var n = long.Parse(line[2]);
        var k = long.Parse(line[3]);
        if ((n != k && hw % n == k) | (n == k && hw % n == 0)) Console.WriteLine("YES");
        else Console.WriteLine("NO");
    }
}