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: Accepted)

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

const int maxn=100010;
int n;
int a[maxn];
char s[maxn];

bool check(int x){
	for(int i=n-x+2;i<=x;i++) if(a[i]!=a[i-1]) return false;
	return true;
}

int main(){

	scanf("%s",s+1); n=strlen(s+1);
	for(int i=1;i<=n;i++) a[i]=s[i]-'0';
	int l=n/2, r=n, ans=l;
	while(l<=r){
		int mid=(l+r)>>1;
		if(check(mid)) ans=mid, l=mid+1; else r=mid-1;
	}
	printf("%d\n", ans);
	return 0;
}