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<iostream>
#include<cstring>
using namespace std;
int main()
{
	char s[100010];
	int l=0,r=0,y=0,ans,ans2,t=0;
	cin>>s;
	ans=1;
	for(int i=0;i<strlen(s);i++){
		if(s[i]=='1'){
			int temp=l;
			l=r;
			r=temp;
			int temp1=l<r?r:l;
			int temp2=l<r?l:r+y;
			temp=temp1<temp2?temp2:temp1;
			if(temp>ans){
				ans=temp; 
			}
			y=1;
			while(i<strlen(s)&&s[i+1]=='1'){
				y++;
				i++;
			}
			if(y>ans){
				ans=y;
			}
			l=0;
		}
		else{
			l++;
		}
	}
	ans2=1;
	l=0;
	r=0;
	y=0;
	t=0;
	for(int i=0;i<strlen(s);i++){
		if(s[i]=='0'){
			int temp=l;
			l=r;
			r=temp;
			int temp1=l<r?r:l;
			int temp2=l<r?l:r+y;
			temp=temp1<temp2?temp2:temp1;
			if(temp>ans){
				ans=temp; 
			}
			y=1;
			while(i<strlen(s)&&s[i+1]=='0'){
				y++;
				i++;
			}
			if(y>ans){
				ans=y;
			}
			l=0;
		}
		else{
			l++;
		}
	}
	if(ans2>ans){
		ans=ans2;
	}
	cout<<ans<<endl;
}