fn main() {
    let mut input = String::new();
    std::io::stdin().read_line(&mut input).unwrap();

    let input = input.trim().as_bytes();
    let mut sum = 0;

    for i in input {
        if 48 <= *i && *i <= 57 {
            sum += i - 48;
        }

    }

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