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: Accepted)

use std::io::stdin;
#[allow(dead_code)]
fn input() -> String {
    let mut s = String::new();
    stdin() .read_line(&mut s) .unwrap();
    s.trim().to_string()
}
#[allow(dead_code)]
fn get_value<T: std::str::FromStr>() -> T {
    input().parse().ok().unwrap()
}
#[allow(dead_code)]
fn get_values_for<T: std::str::FromStr>(times: u64) -> Vec<T> {
    (0..times).map(|_| get_value()).collect()
}
#[allow(dead_code)]
fn get_vector<T: std::str::FromStr>() -> Vec<T> {
    input().split_whitespace().map(|v| v.parse().ok().unwrap()).collect()
}
#[allow(dead_code)]
fn get_vectors_for<T: std::str::FromStr>(times: u64) -> Vec<Vec<T>> {
    (0..times).map(|_| get_vector()).collect()
}

fn main() {
    let input = input();
    let sls = input.chars().collect::<Vec<_>>();

    let len = input.len();
    let mut center = len / 2;
    let (mut f,mut l) = (center, center);

    let temp = sls[f];
    if len % 2 == 0 {
        f -= 1;
        center -= 1;
        if sls[f] != temp {
            println!("{}", len / 2);
            return;
        }
    }

    for i in 1..center+1 {
        if sls[f - i] != temp || sls[l + i] != temp {
            println!("{}", len - f + i - 1);
            return;
        }
    }
    println!("{}", len);
}