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: Accepted)

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace template
{
    class Program
    {
        static void Main(string[] args)
        {
            string s = Console.ReadLine();
            if (s.Length % 2 == 0)
            {
                int ret = 0;
                char hikaku = s[s.Length / 2 - 1];
                for (int i = 0; i < s.Length / 2; i++)
                {
                    if (s[s.Length / 2 - (1 + i)] == hikaku && s[s.Length / 2 + i] == hikaku)
                    {
                        ret++;
                    }
                    else
                    {
                        break;
                    }
                }
                Console.WriteLine(s.Length / 2 + ret);
            }
            else
            {
                int ret = 0;
                char hikaku = s[(s.Length - 1) / 2];
                for (int i = 1; i <= (s.Length - 1) / 2; i++)
                {
                    if (s[(s.Length - 1) / 2 - i] == hikaku && s[(s.Length - 1) / 2 + i] == hikaku)
                    {
                        ret++;
                    }
                    else
                    {
                        break;
                    }
                }
                Console.WriteLine((s.Length + 1) / 2 + ret);
            }
        }
    }
}