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 <cstdio>
#include <iostream> 
#include <string>
#include <vector>
#include <sstream>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <cmath>
#include <cstdlib>
#include <cstring>
#include <functional>

using namespace std;
using ll = long long;

const ll INF = 1e9;
const ll MOD = 1e9 + 7;
int dx[4] = { 1,0,-1,0 };
int dy[4] = { 0,1,0,-1 };

int main()
{
	string s;
	char t;
	int c = 1, i, mx = 0, k;

	cin >> s;
	
	t = s[0];
	for (i = 1; i < s.size(); i++) {
		if (s[i] == t) {
			c++;
		}
		else {
			if (mx < c) {
				mx = c;
			}
			t = s[i];
			c = 1;
		}
	}
	if (mx < c) {
		mx = c;
	}
	k = s.size() + 1 / 2;

	cout << max(mx, k) << endl;
}