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

class Program
{
    static string InputPattern = "Input3";

    static List<string> GetInputList()
    {
        var WillReturn = new List<string>();

        if (InputPattern == "Input1") {
            WillReturn.Add("1 2 2 2");
            //YES
        }
        else if (InputPattern == "Input2") {
            WillReturn.Add("1 2 2 1");
            //NO
        }
        else {
            string wkStr;
            while ((wkStr = Console.ReadLine()) != null) WillReturn.Add(wkStr);
        }
        return WillReturn;
    }

    //No.166 マス埋めゲーム
    static void Main()
    {
        List<string> InputList = GetInputList();
        int[] wkArr = InputList[0].Split(' ').Select(X => int.Parse(X)).ToArray();
        int H = wkArr[0];
        int W = wkArr[1];
        int N = wkArr[2];
        int K = wkArr[3];

        long MasuCnt = H * W;
        long ModVal = MasuCnt % N;
        long LastNo = (ModVal == 0 ? N : ModVal);
        Console.WriteLine(LastNo == K ? "YES" : "NO");
    }
}