use itertools::Itertools;
use proconio::input;
use proconio::marker::Bytes;

fn main() {
    input! {
        c : Bytes
    }

    let c = c.into_iter().map(|c| (c - b'0') as usize).collect_vec();
    println!("{}", c.iter().max().unwrap() - c.iter().min().unwrap());
}