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)

#include <bits/stdc++.h>
using namespace std;

int main() {
	
	string s;
	cin>>s;
	long n,k=0,l;
	n=s.size();
	
	
	if(n>=2){
	for(int i=0;i<n-1;i++){
		if(s.at(i)!=s.at(i+1)){
			
			k++;
			
		}
	}
	vector<long>v(k);
	vector<long>w(k);
	if(k!=0){
	k=0;
	for(int i=0;i<n-1;i++){
		if(s.at(i)!=s.at(i+1)){
			
			v.at(k)=i;
			k++;
			
		}
	}
	l=v.size();
	      
	      for(int i=0;i<l;i++){
	      	w.at(i)=max(n-2*v.at(i),-n+2*v.at(i));
	      }	
	      sort(w.begin(),w.end());
	      if(n%2==0){
	      	cout<<(n+w.at(0))/2<<endl;
	      }
	      else{
	      	cout<<(n+w.at(0))/2-1<<endl;
	      }
	}
	else{
		cout<<n<<endl;
	}
	}
	else{
		cout<<1<<endl;
	}
	
	
}