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 Ruby (2.3.3) (judge verdict: Wrong Answer)

io = STDIN
s=io.gets.chomp.chars
def tri_check(ar,max)
  arr=ar.each_cons(3).map do |x,y,z|
    if x===z && (x==max || y==max)
      x+y
    else
      0
    end
  end.to_a
  arr.max == 0 ? false : arr.max
end
def calc(str)
  ar=str.chunk_while{|x,y|x==y}.map{|x|x.size}
  max=ar.max
  if max*2<str.size
    max+1
  else
    if tri=tri_check(ar,max)
      tri
    elsif ar.first==max || ar.last==max
      max
    else
      max+1
    end
  end
end
puts calc s