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
def input():
	return sys.stdin.readline().strip()

S = input()

length_list = []
length = 1
now = S[0]
for i in range(1, len(S)):
	if now != S[i]:
		length_list.append(length)
		now = S[i]
		length = 1
	else:
		length += 1
length_list.append(length)

ans = max(length_list[0], length_list[-1])
for i in range(1, len(length_list) - 1):
	ans = max(ans, length_list[i] + min(length_list[i - 1], length_list[i + 1]))

print(ans)