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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.util.Scanner;
import java.util.stream.IntStream;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        String S = sc.next();

        System.out.println(solve(S));

        sc.close();
    }

    static int solve(String S) {
        int result = -1;
        int lower = 1;
        int upper = S.length();
        while (lower <= upper) {
            int middle = (lower + upper) / 2;
            if (check(S, middle)) {
                result = middle;
                lower = middle + 1;
            } else {
                upper = middle - 1;
            }
        }

        return result;
    }

    static boolean check(String S, int K) {
        int leftIndex = S.length() - K;
        int rightIndex = K - 1;

        return leftIndex > rightIndex
                || IntStream.rangeClosed(leftIndex, rightIndex).map(S::charAt).distinct().count() == 1;
    }
}