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)
        {
            float[] speed = Console.ReadLine().Trim().Split(' ').Select(x => float.Parse(x)).ToArray();
            float spX = speed[0] * 1000 / 3600;
            float spY = speed[1] * 1000 / 3600;

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

            String look = "YES";

            
            float[] road = Console.ReadLine().Trim().Split(' ').Select(x => float.Parse(x)).ToArray();

            float X = spX, Y = spY;

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