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 C++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <iostream>
#include <algorithm>
#include <string>
#define flush fflush(stdout)
using namespace std;
typedef long long ll;
typedef pair<int, int> P;
typedef pair<ll, int> Pl;
const int mod = (int)1e9 + 7, INF = (int)1e9;
const int di[4] = { 1,0,-1,0 }, dj[4] = { 0,1,0,-1 };


int main(void) {
    int n, i, ans;
    string s;

    cin >> s;

    n = s.size();

    ans = n;
    for (i = 0; i < n - 1; i++) {
        if (s[i] != s[i + 1]) {
            ans = min(ans, max(i + 1, n - i - 1));
        }
    }

    printf("%d\n", ans);

    return 0;
}