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)
k=0
if n%2==0:
  n2=int(n/2)
  k+=n2
  for i in range(n2):
    if '0' in s[n2-i-1:n2+i+1] and '1' in s[n2-i-1:n2+i+1]:
      break
    k+=1
  print(k)
else:
  n3=int((n-1)/2)
  k+=n3
  for i in range(n3+1):
    if '0' in s[n3-i:n3+i+1] and '1' in s[n3-i:n3+i+1]:
      break
    k+=1
  print(k)