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 Rust (1.15.1) (judge verdict: Wrong Answer)

// Try AtCoder
// author: Leonardone @ NEETSDKASU

fn main() {
	let mut stdin = String::new();
    std::io::Read::read_to_string(
    	&mut std::io::stdin(),
        &mut stdin).unwrap();
	let mut stdin = stdin.split_whitespace();
    let mut get = || stdin.next().unwrap();
	
    let s = get().as_bytes();
    
    let mut cur = s[0];
    let mut counts = vec![];
    let mut cnt = 0;
    for &c in &s[..] {
    	if cur == c {
        	cnt += 1;
        } else {
        	counts.push(cnt);
            cur = c;
            cnt = 1;
        }
    }
    counts.push(cnt);
    let mut ans = s.len();
    if counts.len() < 2 {
    	println!("{}", counts[0]);
        return;
    }
     if counts.len() == 2 {
	    ans = std::cmp::max(
        	counts[0],
            counts[1]);
    } else if counts.len() > 2 {
    	let d = (counts.len() + 1) / 2;
        let mut tmp = 0;
        for i in 0..d{
        	tmp += counts[i];
        }
        ans = tmp;
    	for i in d..counts.len() {
            tmp += counts[i];
        	tmp -= counts[i - d];
        	ans = std::cmp::min(
            	ans,
                tmp);
        }
    }
    
    println!("{}", ans);
}