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 <vector>
#include <queue>
#include <stack>
#include <string>
#include <iomanip>
#include <map>
#include <set>
#include <cmath>
#include <cstdio>
using namespace std;
#define rep(i,n) for(int (i)=0;(i)<(n);(i)++)
#define FOR(i,m,n) for(int (i)=(m);(i)<(n);(i)++)
#define All(v) (v).begin(),(v).end()
typedef long long ll;

int main(){
    string S;
    cin >> S;
    int N = S.size();
    int res = N;
    rep(i,N-1){
        if(S[i]!=S[i+1]){
            res = min(res,max(i+1,N-i-1));
        }
    }
    cout << res << endl;
    return 0;
}