using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;
using System.Globalization;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static int[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var c = NList;
        var (l, r, m, k) = (c[0], c[1], c[2], c[3]);
        var min = (long)l * k;
        var max = (long)r * k;
        WriteLine(min % m == 0 || min / m != max / m ? "Yes" : "No");
    }
}