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: Wrong Answer)

S = input()
idx = 0
cnts = []
while idx < len(S):
    char = S[idx]
    cnt = 0
    while idx < len(S) and S[idx] == char:
        idx += 1
        cnt += 1
    cnts.append(cnt)
if len(cnts) <= 2:
    print(max(cnts))
    quit()
ans = (len(S) + 1) // 2
for i in range(len(cnts) - 2):
    ans = max(ans, min(cnts[i] + cnts[i + 1], cnts[i + 1] + cnts[i + 2]))
cnt_sum = sum(cnts)
for _ in range(2):
    cand = 0
    for cnt in cnts:
        if cand > cnt_sum // 2:
            break
        cand += cnt
    ans = max(ans, cand)
    cnts = cnts[::-1]
print(ans)