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 (2.4.0) (judge verdict: Wrong Answer)

import sys,queue,math,copy,itertools
from fractions import gcd
sys.setrecursionlimit(10**7)
LI = lambda : [int(x) for x in sys.stdin.readline().split()]
_LI = lambda : [int(x)-1 for x in sys.stdin.readline().split()]
NI = lambda : int(sys.stdin.readline())

S = input()
ans = 0
cnt = 1
lastx = S[0]
scnt = []
for x in S[1:]+'9':
    if x != lastx:
        scnt.append(cnt)
        lastx = x
        cnt = 0
    cnt += 1

ttl = sum(scnt)
scnt = [0] + scnt + [0]
acc = 0
for i in range(1,len(scnt)-1):
    pl = 0
    if acc > 0:
        pl = min(acc,scnt[i+1])
    if ttl - acc - scnt[i] > 0:
        pl = max(pl,min(scnt[i-1],ttl - acc - scnt[i]))
    ans = max(ans,scnt[i] + pl)
    acc += scnt[i]
print (ans)