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;
const int N=1e5+11;
int n,ans=N,l[N],r[N],m[N],cnt;
char s[N];
int main(){
//	freopen("ex.in","r",stdin);
	scanf("%s",s+1);
	n=strlen(s+1);
	for(int i=1;i<=n;++i){
		if(s[i]=='1'&&(s[i-1]=='0'||i==1)) cnt++,m[cnt]++,l[cnt]=r[cnt-1];
		else if(s[i]=='1'&&s[i-1]=='1') m[cnt]++;
		else if(s[i]=='0') r[cnt]++;
	}
	if(cnt==0){
		printf("0");
		return 0;
	}
	if(cnt==1){
		if(l[1]==0) printf("%d",r[1]);
		else if(r[1]==0) printf("%d",l[1]);
		else printf("%d",min(l[1],r[1]));
		return 0;
	}
	for(int i=1;i<=cnt;++i) ans=min(ans,m[i]+min(l[i],r[i]));
	printf("%d",ans);
	return 0;
}