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

namespace pj12
{
    class Program
    {
        static void Main(string[] args)
        {
            double[] speed = Console.ReadLine().Trim().Split(' ').Select(x => double.Parse(x)).ToArray();
            double spX = speed[0] * 1000 / 3600;
            double spY = speed[1] * 1000 / 3600;

            int coner = int.Parse(Console.ReadLine());

            String look = "YES";

            double[] road = new double[coner];
            double[] line = Console.ReadLine().Trim().Split(' ').Select(x => double.Parse(x)).ToArray();
            for (int i = 0; i < coner; i++)
            {
                road[i] = line[i];
            }

            double X = spX, Y = spY;

            for (int i = 0; i < road.Length; i++)
            {
                double kyori = spY * road[i] / spX;
                if (kyori > road[i + 1])
                {
                    look = "NO";
                    break;
                }
            }
            Console.WriteLine(look);
        }
    }
}