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)

S = gets.chomp.split("").map(&:to_i)

def reverse(s,e,arr)
    (s..e).each{ |i|
        arr[i] = arr[i] == 0 ? 1 : 0
    }
    return arr
end

def finish?(arr)
    return arr.uniq.length == 1
end

def hoge(orgarr)
    cnt = 0
    scopy = orgarr.clone
    arr = []
    memo = scopy[0]
    loop{
        if scopy.shift == memo then
            cnt += 1
        else
            arr << cnt
            cnt = 1
            memo = scopy[0]
        end

        if scopy.length == 0 then
            arr << cnt
            break
        end
    }
    return arr
end

ans = S.length

loop{
    arr = hoge(S)

    if arr[0] > arr[-1] then
        ans = S.length - arr[-1] if ans > S.length - arr[-1] 
        reverse(0, S.length - arr[-1] - 1, S)
    else
        ans = S.length - arr[0] if ans > S.length - arr[0] 
        reverse(arr[0], S.length-1, S)
    end

    if finish?(S) then
        puts ans
        break
    end
}