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 PyPy3 (7.3.0) (judge verdict: Accepted)

import math
#import numpy as np
import queue
import bisect
from collections import deque,defaultdict
import heapq as hpq
from sys import stdin,setrecursionlimit
#from scipy.sparse.csgraph import dijkstra
#from scipy.sparse import csr_matrix
ipt = stdin.readline
setrecursionlimit(10**7)

def main():
    s = input()
#    s = "1"*10**5
    n = len(s)
    if n&1:
        t = 1
        sf = n//2-1
        so = n//2+1
        ss = s[n//2]
        while sf >= 0:
            if s[so] == ss == s[sf]:
                t += 1
                sf -= 1
                so += 1
            else:
                break
        print(t+n//2)
    else:
        if s[n//2] == s[n//2-1]:
            ss = s[n//2]
            t = 1
            sf = n//2-2
            so = n//2+1
            while sf >= 0:
                if s[so] == ss == s[sf]:
                    t += 1
                    sf -= 1
                    so += 1
                else:
                    break
            print(n//2+t)
        else:
            print(n//2)


    return None

if __name__ == '__main__':
    main()