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: Runtime Error)

#include <algorithm>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <deque>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

using std::cerr;
using std::cin;
using std::cout;
using std::endl;

int main(void){
  cout << std::fixed << std::setprecision(10);
  cin.tie(0);
  std::ios::sync_with_stdio(false);

  std::string s;
  cin>>s;
  int result=0;

  std::vector<int> left,right,boarder;

  left.push_back(0);
  for(int i=1;i<s.size();i++){
    if(s[i-1]!=s[i]){
      if(boarder.empty()){
        boarder.push_back(i-1);
        left.push_back(i);
      }else{
        boarder.push_back(i-1);
        right.push_back(i-1);
        left.push_back(i);
      }


    }
  }
  if(left.empty()){
    cout<<s.size()<<endl;
    return 0;
  }
  if(right.empty()){
    right.push_back(s.size()-1);
  }

  for(int i=0;i<right.size();i++){
    int temp=std::min(right[i]-left[i]+1,std::max(boarder[i]+1,(int)(s.size()-boarder[i]-1)));
    result=std::max(temp,result);
  }
  cout<<result<<endl;
  
  return 0;
}