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;
	
	vector<int> a;
	int tmp=1;
	int flag=s[0]-'0';
	for(int i=1;i<s.size();i++){
		if(s[i]-'0'==flag){
			tmp++;
		}else{
			a.push_back(tmp);
			tmp=1;
			flag=abs(flag-1);
		}
	}
	a.push_back(tmp);
	
	if(a.size()==1){
		cout<<s.size()<<endl;
	}else if(a.size()==2){
		cout<<max(a[0],a[1])<<endl;
	}else{
		int ans=0;
		for(int i=0;i<a.size()-1;i++){
			int tmp=a[i]+a[i+1];
			ans=max(ans,tmp);
		}
		for(int i=0;i<a.size();i++)ans=max(ans,a[i]);
		cout<<ans<<endl;
	}
}