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 Go (1.6) (judge verdict: Wrong Answer)

// Package main provides
//
// File:  main.go
// Author: ymiyamoto
//
// Created on Wed Feb  6 12:22:28 2019
//
package main

import "fmt"

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

func max(a, b int) int {
	if a < b {
		return b
	}
	return a
}

func main() {
	var S string
	fmt.Scan(&S)

	ans := 1 << 60
	for i := range S {
		if i+1 < len(S) {
			if S[i] != S[i+1] {
				ans = min(ans, max(i+1, len(S)-i-1))
			}
		}
	}

	if ans == 1<<60 {
		if S[0] == '0' {
			fmt.Println(0)
		} else {
			fmt.Println(len(S))
		}
	} else {
		fmt.Println(ans)
	}
}