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.*;
import static java.lang.Math.*;
import java.math.BigInteger;

public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		
		// 入力
		String s = sc.next();
		
		// 計算
		int result = Integer.MAX_VALUE;
		boolean isZero = false;
		ArrayList<Integer> list = new ArrayList<Integer>();
		int cnt = 0;
		int sum = 0;
		for(int i = 0; i < s.length(); i++){
		    if(i == 0){
		        if(s.charAt(i) == '0') isZero = true;
		    }
		    if((s.charAt(i) == '0' && isZero)||(s.charAt(i) == '1' && !isZero)){
		        cnt++;
		    }else{
		        list.add(cnt);
		        sum += cnt;
		        cnt = 1;
		        isZero = !isZero;
		    }
		}
		list.add(cnt);
		sum += cnt;
		if(list.size() == 1){
		    result = list.get(0);
		}else{
		    int temp = 0;
		    for(int i = 0; i < list.size(); i++){
		        temp += list.get(i);
		        result = min(result, max(sum - temp, temp));
		    }
		}
		
		// 出力
		System.out.println(result);
	}
}