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

public class Program
{

    public void Proc()
    {
        string inpt = Reader.ReadLine();
        bool isAns4 = IsKadomatu(inpt.Replace('?', '4'));
        bool isAns1 = IsKadomatu(inpt.Replace('?', '1'));
        string ans = "" + (isAns1 ? "1" : "") + (isAns4 ? "4" : "");
        Console.WriteLine(ans);
    }

    private bool IsKadomatu(string inpt) {
        int[] tmp = inpt.Split(' ').Select(a => int.Parse(a)).ToArray();
        if(tmp.Max()==tmp[1]||tmp.Min()==tmp[1]) {
            return true;
        }
        return false;
    }



    public class Reader
    {
        private static StringReader sr;
        public static bool IsDebug = false;
        public static string ReadLine()
        {
            if (IsDebug)
            {
                if (sr == null)
                {
                    sr = new StringReader(InputText.Trim());
                }
                return sr.ReadLine();
            }
            else
            {
                return Console.ReadLine();
            }
        }
        private static string InputText = @"



? 2 3




";
    }

    public static void Main(string[] args)
    {
#if DEBUG
        Reader.IsDebug = true;
#endif
        Program prg = new Program();
        prg.Proc();
    }
}