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;

public class Main implements Runnable {

    public static void main(String[] args) {
        new Thread(null, new Main(), "", 128 * 1024 * 1024).start();
    }

    public void run() {
        Scanner sc = new Scanner(System.in);
        String s = sc.next();

        int size = s.length();
        int[] sequence = new int[100000];
        int idx = 0;
        int prevIdx = 0;
        int prev = s.charAt(0) - '0';
        for (int i = 1; i < size; i++) {
            int current = s.charAt(i) - '0';
            if (current != prev) {
                sequence[idx] = i - prevIdx;
                prevIdx = i;
                prev = current;
                idx++;
            }
        }
        sequence[idx] = size - prevIdx;

        int sum = 0;
        int least = Integer.MAX_VALUE;
        for (int i = 0; i <= idx; i++) {
            sum += sequence[i];
            least = Math.min(Math.max(sum, size - sum), least);
        }
        System.out.println(least);
    }
}