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

namespace YukiCoder
{
    class Program
    {
        static void Main(string[] args)
        {
            var na = Console.ReadLine().Split().Select(double.Parse).ToArray();
            int nn = int.Parse(Console.ReadLine());
            var nb = Console.ReadLine().Split().Select(double.Parse).ToArray();

            var va = nb.Skip(1).Where((z, i) => z / na[1] < nb[i] / na[0]);
            //va.ToList().ForEach(Console.WriteLine);

            if (va.Count() > 0) Console.WriteLine("NO");
            else Console.WriteLine("YES");
            Console.ReadLine();
        }
    }
}