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 Python (2.7.6) (judge verdict: Wrong Answer)

#!/usr/bin/python

import sys

def solution(S):
    while True:
        left = S.find("1")
        right = S.rfind("1")

        if left == right:
            if left == -1:
                return len(S)
            elif left == 0 or left == len(S) - 1:
                return len(S) - 1
            elif left == (len(S) - left - 1):
                return left + 1
            else:
                return max(left, len(S) - left - 1)
        else:
            next_S = ""
            for i in xrange(left, right + 1):
                next_S += ("0" if S[i] == "1" else "1")
            S = next_S

def main(argv):
    line = sys.stdin.readline()
    while line:
        S = line.rstrip("\n")
        print solution(S)
        line = sys.stdin.readline()

if __name__ == "__main__":
    main(sys.argv)