using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
 
namespace olymptest
{
    class Program
    {
        static void Main(string[] args)
        {
            string numb = Console.ReadLine();
            char[] numbchar = new char[numb.Length];                     
            int x = numb.Length;
            if (x < 2002)                       
            {
                for (int i = 0; i < numb.Length / 2; i++)
                {
                    x--;          
                        numbchar[i] = Convert.ToChar(numb[i]);
                        numbchar[x] = numbchar[i];   
                    if ((x==numb.Length/2) &&  (Convert.ToInt32(numb[x]) > Convert.ToInt32(numb[i])))
                    {
                        numbchar[i]++;
                        numbchar[x]++;
                    }
                }
 
                if (numb.Length % 2 != 0)
                {
                    numbchar[numb.Length / 2] = Convert.ToChar(numb[numb.Length / 2]);
                    if (Convert.ToInt32(numb[numb.Length / 2 + 1]) > Convert.ToInt32(numb[numb.Length / 2]))
                    {                        
                        numbchar[numb.Length/2]++;
                    }
 
                }
            }
            Console.WriteLine(numbchar);
            Console.ReadLine();
        }
    }
}