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 Lua (5.3.2) (judge verdict: Accepted)

local s = io.read()
local n = #s
local prv = s:sub(1, 1)
local nxt = ""
local from = 1
local ret = 1
local mma, mmi = math.max, math.min
for i = 2, n do
  nxt = s:sub(i, i)
  if prv ~= nxt then
    ret = mma(ret, mmi(i - 1, n + 1 - from))
    prv = nxt
    from = i
  end
end
ret = mma(ret, mmi(n, n + 1 - from))
print(ret)