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 (3.4.3) (judge verdict: Accepted)

def solve(s):
    n = len(s)

    if n == 1:
        return 1
    if n == 2:
        return 2 if s[0] == s[1] else 1

    ci = n // 2
    c = s[ci]
    if n & 1:
        for di in range(1, ci + 1):
            if c == s[ci - di] == s[ci + di]:
                pass
            else:
                return ci + di
        return n
    if c != s[ci - 1]:
        return ci
    for di in range(1, ci):
        if c == s[ci - di - 1] == s[ci + di]:
            pass
        else:
            return ci + di
    return n


print(solve(input()))