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()
ss = []

key = s[0]
cnt = 1
for i in range(1,len(s)):
    if key == s[i]:
        cnt += 1
    else:
        ss.append(cnt)
        key = s[i]
        cnt = 1

ss.append(cnt)

ans = 0
maxs = max(ss)
if len(ss)==1 or len(ss)==2:
    ans = maxs
elif len(ss)==3:
    ans = max(min(ss[1]+ss[0],ss[1]+ss[2]),max(ss))

else:
# 端っこだったらこれで拾う。
    tmpmax = max(ss[0],ss[len(ss)-1])

# 端以外のMAX＋端じゃない長い方or短い端
    for i in range(1,len(ss)-1 ):
        if ss[i] == maxs:
            if i == 1:
                if ss[0] > ss[2]:
                    tmp = maxs + ss[2] 
                else:
                    tmp = maxs + ss[0]
            elif i == len(ss)-2:
                if ss[len(ss)-1] > ss[len(ss)-3]:
                    tmp = maxs + ss[len(ss)-3]
                else:
                    tmp = maxs + ss[len(ss)-1]
            else:
                tmp= maxs+max(ss[i-1],ss[i+1])

            if tmp > tmpmax:
                tmpmax = tmp
        else:
            pass

    ans = tmpmax

print(ans)