use std::io::*;

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<u8> = itr.next().unwrap().bytes().collect();

    let mut ans = 0;
    for &c in s.iter() {
        if 48 <= c && c <= 57 {
            ans += c - 48;
        }
    }
    println!("{}", ans)
}