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: Accepted)

S = input()

N = len(S)
L = []
temp = S[0]
c = 1
for i in range(1, N-1):
    if S[i] == temp:
        c += 1
    else:
        L.append(c)
        c = 1
        temp = S[i]
if S[N-1] == temp:
    c += 1
else:
    L.append(c)
    c = 1
L.append(c)

ans = N
while len(L) >= 3:
    if L[0] > L[-1]:
        ans = min(ans, N-L[-1])
        L[-2] += L[-1]
        L.pop(-1)
    else:
        ans = min(ans, N-L[0])
        L[1] += L[0]
        L.pop(0)
        
if len(L) == 2:
    ans = min(ans, max(L))
    
print(ans)