use std::io::*;

fn manacher(s: &[char]) -> Vec<usize> {
    let mut l = 0;
    let mut r = 0;
    let n = s.len();
    let mut res = vec![0; n];

    for i in 0..n {
        let mut j = 0;
        if i <= r {
            j = std::cmp::min(res[l * 2 - i], r - i);
        }
        while i >= j && i + j < n && s[i - j] == s[i + j] {
            j += 1;
        }
        res[i] = j;

        if i + j - 1 >= r {
            l = i;
            r = i + j - 1;
        }
    }
    res
}

fn main() {
    let mut s: String = String::new();
    std::io::stdin().read_to_string(&mut s).ok();
    let mut itr = s.trim().split_whitespace();
    let s: Vec<char> = itr.next().unwrap().chars().collect();
    let n = s.len();
    let mut t = Vec::new();
    t.push('a');
    for i in 0..n {
        t.push(s[i]);
        t.push('a');
    }
    let res = manacher(&t);
    let mut ans = 1;
    for i in 0..res.len() {
        let mut r = res[i] >> 1;
        if res[i] % 2 == 0 {
            r += r - 1;
        } else {
            r <<= 1;
        }
        if r == n {
            r -= 2;
        }
        ans = std::cmp::max(ans, r);
    }
    println!("{}", ans);
}