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

namespace AtCoder
{
    class Program
    {
        private static string Read() { return Console.ReadLine(); }
        private static int ReadInt() { return int.Parse(Read()); }
        private static long ReadLong() { return long.Parse(Read()); }
        private static double ReadDouble() { return double.Parse(Read()); }
        private static int[] ReadInts() { return Array.ConvertAll(Read().Split(), int.Parse); }
        private static long[] ReadLongs() { return Array.ConvertAll(Read().Split(), long.Parse); }
        private static double[] ReadDoubles() { return Array.ConvertAll(Read().Split(), double.Parse); }

        private static int Solve(string S)
        {
            int N = S.Length;
            var values = new List<int>();
            int value = 0;
            for (int i = 0; i < N; ++i)
            {
                ++value;
                if (i + 1 == N || S[i] != S[i + 1])
                {
                    values.Add(value);
                    value = 0;
                }
            }
            if (values.Count == 1) { return values[0]; }
            int max = 0;
            int maxi = 0;
            for (int i = 0; i + 1 < values.Count; ++i)
            {
                if (values[i] + values[i + 1] > max)
                {
                    max = values[i] + values[i + 1];
                    maxi = i;
                }
            }
            int a = 0;
            int b = 0;
            for (int i = 0; i < values.Count; ++i)
            {
                if (i <= maxi) { a += values[i]; }
                else           { b += values[i]; }
            }
            return Math.Max(a, b);
        }

        static void Main(string[] args)
        {
            Console.WriteLine(Solve(Read()));
        }
    }
}