using System.IO;
using System;

class Program
{
    static void Main()
    {
        string s = Console.ReadLine();
            int n = 0;
            int m = s.Length - 1;
            bool polindrom = true;
            bool have = false;
            while (n <= m)
            {
                if (s[n] != s[m])
                {
                    polindrom = false;
                }
                if (s[m] != s[0] || s[n] != s[0])
                {
                    have = true;
                }
                n += 1;
                m -= 1;
            }

            if (!have)
            {
                Console.WriteLine(-1);
            }
            else
            {
                if (polindrom)
                {
                    Console.WriteLine(s.Length-1);
                }
                else
                {
                    Console.WriteLine(s.Length);
                }
            }
    }
}