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)

use std::io::*;

fn main() {
    let stdin = stdin();
    let mut lock = stdin.lock();
    let mut str1 = String::new();
    lock.read_line(&mut str1).unwrap();
    let vec:Vec<_> = str1.trim().split_whitespace().
    next().unwrap().bytes().collect();/*.map(|x|
    match(x) {
        48 => false,
        49 => true,
        _ => unreachable!(),
    }).collect();
    */
    let mut sanjo = vec.len() as usize;
    for (i, j) in vec.iter().enumerate() {
        //        println!(": {}, {}, {}", i, j, vec[0]);
        if *j != vec[0] {
            if i < vec.len() - i {
                sanjo = vec.len() - i;
            } else {
                sanjo = i;
            }
            break;
        }
    }
    /*
    for (i, j) in vec.iter().rev().enumerate() {
        if *j != vec[vec.len() - 1] {
            if sanjo < vec.len() - i {
                sanjo = vec.len() - i;
            }
            break;
        }
    }
    */
    println!("{}", sanjo);
}