Problem:
Score : 500 points

Problem Statement

You are given a string S consisting of 0 and 1.
Find the maximum integer K not greater than |S| such that we can turn all the characters of S into 0 by repeating the following operation some number of times.

Choose a contiguous segment [l,r] in S whose length is at least K (that is, r-l+1\geq K must be satisfied). For each integer i such that l\leq i\leq r, do the following: if S_i is 0, replace it with 1; if S_i is 1, replace it with 0.

Constraints

1\leq |S|\leq 10^5

S_i(1\leq i\leq N) is either 0 or 1.

Input

Input is given from Standard Input in the following format:

S

Output

Print the maximum integer K such that we can turn all the characters of S into 0 by repeating the operation some number of times.

Sample Input 1

010

Sample Output 1

2

We can turn all the characters of S into 0 by the following operations:

Perform the operation on the segment S[1,3] with length 3. S is now 101.

Perform the operation on the segment S[1,2] with length 2. S is now 011.

Perform the operation on the segment S[2,3] with length 2. S is now 000.

Sample Input 2

100000000

Sample Output 2

8

Sample Input 3

00001111

Sample Output 3

4

Solution in C# (Mono 4.6.2.0) (judge verdict: Wrong Answer)

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

public class Program
{

    public void Proc()
    {
        string inpt = Reader.ReadLine();
        List<string> list = new List<string>();
        int idx = 0;
        int ans = 0;
        for (int i = 1; i < inpt.Length; i++) {
            if(inpt[i]!=inpt[i-1]) {
                list.Add(inpt.Substring(idx, i-idx));
                idx = i;
                if(inpt.Length %2 ==0&&i==inpt.Length/2) {
                    Console.WriteLine(inpt.Length/2);
                    return;
                }
            }
        }
        list.Add(inpt.Substring(idx));
        idx = 0;
        for (int i = 0; i < list.Count; i++) {
            if(idx <= inpt.Length/2&&idx+list[i].Length>inpt.Length/2) {
                ans = Math.Min(idx + list[i].Length-1, inpt.Length - idx);
                break;
            }
            idx += list[i].Length;
        }
        Console.WriteLine(ans);
    }


    public class Reader
    {
        private static StringReader sr;
        public static bool IsDebug = false;
        public static string ReadLine()
        {
            if (IsDebug)
            {
                if (sr == null)
                {
                    sr = new StringReader(InputText.Trim());
                }
                return sr.ReadLine();
            }
            else
            {
                return Console.ReadLine();
            }
        }
        private static string InputText = @"



1111101



";
    }

    public static void Main(string[] args)
    {
#if DEBUG
        Reader.IsDebug = true;
#endif
        Program prg = new Program();
        prg.Proc();
    }
}