use std::io::{self, Read};

fn read_stdin() -> Vec<String> {
    let mut buffer = String::new();
    io::stdin().read_to_string(&mut buffer).ok();
    buffer.trim().split('\n').map(|s| s.to_string()).collect()
}

fn main() {
    let input = read_stdin();
    println!("{}",
        &input[0]
            .chars()
            .fold(0, |acc, c| {
                if c.is_digit(10) {
                    acc + c.to_digit(10).unwrap()
                } else {
                    acc
                }
            })
    );
}