using System;
using System.Linq;
class Program {
    static void Main() {
        long[] rl = Console.ReadLine().Split().Select(long.Parse).ToArray();
        long h = rl[0], w = rl[1], n = rl[2], k = rl[3];
        Console.WriteLine((h * w - k) % n == 0 ? "YES" : "NO");
    }
}