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 Perl (v5.18.2) (judge verdict: Accepted)

#!/usr/bin/perl
#abc083_d.pl
#Wed Jan 10 20:31:35 2018
#

use warnings;
use strict;

my $s = <STDIN>;
chomp $s;

my @target = split("",$s);

my $num = 1;
my $answer = 9999999;

while ($num<=$#target){
	if ($target[$num] != $target[$num-1]){
		my $answercand = 0;
		if ($#target-$num+1 > $num){
			$answercand = $#target-$num+1;
		}else{
			$answercand = $num;
		}
		if ($answer > $answercand){
			$answer = $answercand;
		}
	}
	$num++;
}

if ($answer == 9999999){
	$answer = $#target+1;
}

print $answer,"\n";