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# (.NET Core 3.1.201) (judge verdict: Wrong Answer)

using System;

public class Hello
{
    public static void Main()
    {
        var s = Console.ReadLine().Trim();
        var sL = s.Length;
        if (sL == 1) Console.WriteLine(1);
        else if (sL == 2) Console.WriteLine(check2(s));
        else
        {
            var a = sL / 2;
            if (sL % 2 == 0) Console.WriteLine(a + check0(s, a));
            else Console.WriteLine(check1(s, a) + 1);
        }
    }
    static int check2(string s) => s[0] == s[1] ? 2 : 1;
    static int check1(string s, int a)
    {
        var s0 = s[a];
        var count = 1;
        for (int i = 1; i <= a; i++)
        {
            if (s[a - i] == s0 && s[a + i] == s0) count += 2;
            else return count;
        }
        return count;

    }
    static int check0(string s, int a)
    {
        if (s[a - 1] != s[a]) return 0;
        var s0 = s[a - 1];
        var count = 2;
        for (int i = 1; i < a; i++)
        {
            if (s[a + i] == s0 && s[a - 1 - i] == s0) count++;
            else return count;
        }
        return count;
    }
}