#![allow(non_snake_case)]

use std::cmp;
use std::io::{ self, prelude::* };

macro_rules! pick {
    ($tokens:expr) => {
        $tokens.next().unwrap().parse().expect("parse error")
    }
}

fn read() -> String {
    let mut s = String::new();
    io::stdin().read_to_string(&mut s).expect("i/o error");
    s
}

fn f_odd(S: &[char]) -> u32 {
    let mut res = 0;
    for i in 0..S.len() {
        let mut cur = 1;
        for j in 1.. {
            let l = i as i64 - j as i64;
            let r = i as i64 + j as i64;
            if l < 0 || r >= S.len() as i64 { break; }
            if S[l as usize] == S[r as usize] {
                cur += 2;
            }
        }
        res = cmp::max(res, cur);
    }
    res
}

fn f_even(S: &[char]) -> u32 {
    if S.len() < 2 { return 0; }

    let mut res = 0;
    for i in 1..S.len() {
        let mut cur = 0;
        for j in 0.. {
            let l = i as i64 - j as i64 - 1;
            let r = i as i64 + j as i64;
            if l < 0 || r >= S.len() as i64 { break; }
            if S[l as usize] == S[r as usize] {
                cur += 2;
            }
        }
        res = cmp::max(res, cur);
    }
    res
}

fn main() {
    let s = read();
    let mut tokens = s.split_whitespace();

    let S: String = pick!(tokens);
    let S: Vec<_> = S.chars().collect();

    let ans = cmp::max(f_odd(&S), f_even(&S));

    println!("{}", ans);
}