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: Wrong Answer)

/// I won't go back on my word, that's my ninja way!
#include<bits/stdc++.h>
using namespace std;
const int N = 2e5+5 ;
string str ;
int lst[2] = {-1,-1} ,cnt[2] ;
int solve(int z){
    int ret = max(cnt[0] ,cnt[1]) ;
    for(int i=0;i<str.size();++i){
        if(i>lst[z]) break;
        if(str[i]-'0' == z) continue;
        ret = min(ret ,(int)str.size()-i) ;
        z ^= 1 ;
    }
    return ret;
}
int main(){
    cin >> str ;
    for(int i=str.size()-1;i>=0;--i){
        ++cnt[str[i]-'0'] ;
        if(~lst[str[i]-'0'])continue;
        lst[str[i]-'0'] = i ;
    }
    cout << max(solve(0) ,solve(1)) ;
    return 0 ;
}