using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static long NN => long.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static int[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var s = ReadLine();
        var ans = 0;
        for (var i = 0; i < s.Length; ++i)
        {
            var tmp = 1;
            for (var j = 1; j < s.Length; ++j)
            {
                if (i - j < 0 || i + j >= s.Length) break;
                if (s[i - j] == s[i + j]) tmp += 2;
            }
            ans = Math.Max(ans, tmp);
            if (i + 1 < s.Length && s[i] == s[i + 1])
            {
                tmp = 2;
                for (var j = 1; j < s.Length; ++j)
                {
                    if (i - j < 0 || i + j + 1 >= s.Length) break;
                    if (s[i - j] == s[i + j + 1]) tmp += 2;
                }
                ans = Math.Max(ans, tmp);
            }
        }
        WriteLine(ans);
    }
}