using System;
using System.Diagnostics;

namespace yukicoder
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] str = Console.ReadLine().Split(' ');

            int count = 0;
            for (int i = 1; i <= 10; i++)
            {
                for(int j=0;j<str.Length;j++)
                {
                    string a = i.ToString();
                    if(a==str[j])
                    {
                        break;
                    }
                    else if(str[j]!=a)
                    {
                        count++;
                        if (count == str.Length)
                        {
                            break;
                        }
                        else
                        {
                            continue;
                        }
                    }

                }
                if (count == str.Length)
                {
                    Console.WriteLine(i.ToString());

                    break;
                }
                else
                {
                    count = 0;
                }
            }
        }
    }
}