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

class Program
{
    public void Proc()
    {
        Reader.IsDebug = false;
        int mojiCount = int.Parse(Reader.ReadLine());
        string inpt = Reader.ReadLine();
        bool ans = true;
        if (inpt.Length == 1)
        {
            ans = false;
        }
        else if (inpt.Length == 2)
        {
            if (inpt[0] == inpt[1])
            {
                ans = true;
            }
            else
            {
                ans = false;
            }
        }

        Console.WriteLine(ans ? "YES" : "NO");

    }



    public class Reader
    {
        public static bool IsDebug = true;
        private static String PlainInput = @"
 

14
00110101101010

 
";
        private static System.IO.StringReader Sr = null;
        public static string ReadLine()
        {
            if (IsDebug)
            {
                if (Sr == null)
                {
                    Sr = new System.IO.StringReader(PlainInput.Trim());
                }
                return Sr.ReadLine();
            }
            else
            {
                return Console.ReadLine();
            }
        }

    }
    static void Main()
    {
        Program prg = new Program();
        prg.Proc();
    }
}