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

     
    public class Program
    {
        public void Proc() {
            Reader.IsDebug = false;
            int[] inpt = Reader.ReadLine().Split(' ').Select(a=>int.Parse(a)).ToArray();

            int spdX = inpt[0];
            int spdY = inpt[1];

            int pointCount = int.Parse(Reader.ReadLine());
            inpt = Reader.ReadLine().Split(' ').Select(a=>int.Parse(a)).ToArray();

            String ans = "YES";
            for(int i=0; i<inpt.Length-1; i++) {
                decimal pos = inpt[i];
                decimal pos2 = spdY*pos/spdX;
                if(pos2 > inpt[i+1]) {
                    ans = "NO";
                    break;
                }
            }
            Console.WriteLine(ans);
        }

        


        public class Reader {
            public static bool IsDebug = true;
            private static System.IO.StringReader SReader;
            private static string InitText = @"







19 57
9
5 16 48 144 432 1296 3888 11664 34992






";
            public static string ReadLine() {
                if(IsDebug) {
                    if(SReader == null) {
                        SReader = new System.IO.StringReader(InitText.Trim());
                    }
                    return SReader.ReadLine();
                } else {
                    return Console.ReadLine();
                }
            }
        }
        public static void Main(string[] args)
        {
            Program prg = new Program();
            prg.Proc();
        }
    }