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: Accepted)

using System;

class D
{
	static void Main()
	{
		var s = Console.ReadLine();
		var n = s.Length;

		var k = (n + 1) / 2;
		var m = (n - 1) / 2;
		if (n % 2 == 0)
		{
			if (s[m] == s[m + 1])
			{
				k++;
				for (int i = 1; i <= m && s[m - i] == s[m] && s[m + 1 + i] == s[m]; i++, k++) ;
			}
		}
		else
		{
			for (int i = 1; i <= m && s[m - i] == s[m] && s[m + i] == s[m]; i++, k++) ;
		}
		Console.WriteLine(k);
	}
}