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



public class palindrom
{
    public static void rekurze(int i, int j, int hloubka)
    {
        if (i < j)
        {
            if (hlavni.s[i] == hlavni.s[j])
            {
                rekurze(i + 1, j - 1, hloubka + 2);
            }
            else if ( (i < (j-1)) && (hlavni.s[i] == hlavni.s[j-1]) && (hlavni.s[i+1]!=hlavni.s[j]) )
            {
                rekurze(i + 1, j - 2, hloubka + 2);
            }
            else
            {
                int index = i;
                while ((index < j) && (hloubka + (j - index + 1) > hlavni.max))
                {
                    int index2 = j;
                    while ((index2 > index) && (hlavni.s[index] != hlavni.s[index2]) && (hloubka + (index2 - index + 1) > hlavni.max))
                    {
                        index2 = index2 - 1;
                    }
                    if (index == index2)
                    {
                        if ((hloubka + 1) > hlavni.max)
                        {
                            hlavni.max = (hloubka + 1);
                        }
                    }
                    else
                    {
                        if (hlavni.s[index] == hlavni.s[index2])
                        {
                            rekurze(index + 1, index2 - 1, hloubka + 2);
                        }
                    }
                    index = index + 1;
                }
            }
        }
        else if (i == j)
        {
            if ((hloubka + 1) > hlavni.max)
            {
                hlavni.max = (hloubka + 1);
            }
        }
        else
        {
            if ((hloubka) > hlavni.max)
            {
                hlavni.max = (hloubka);
            }
        }
    }
}


class hlavni
{
    public static int max = 0;
    public static string s = "";
    public static void Main()
    {
        int i = 0;
        int j = 0;
        try
        {
            using (StreamReader sr = new StreamReader("vstup.txt"))
            {
                String line;
                while ((line = sr.ReadLine()) != null)
                {
                    s = line;
                }
            }
        }
        catch (Exception e)
        {
            Console.WriteLine("The file could not be read:");
            Console.WriteLine(e.Message);
        }
        j = s.Length - 1;

        palindrom.rekurze(i, j, 0);
        Console.WriteLine(max);
        Console.ReadLine();
    }
}