fn main() {
    let stdin = std::io::read_to_string(std::io::stdin()).unwrap();
    let mut stdin = stdin.lines();

    let s: String = stdin.next().unwrap().parse().unwrap();

    use std::io::Write;
    let mut out = std::io::BufWriter::new(std::io::stdout().lock());
    out.write_all(output(solve(s)).as_bytes()).unwrap();
}

fn solve(s: String) -> u8 {
    s.bytes()
        .map(|s| match s {
            b'0' => 10,
            s => s - b'0',
        })
        .sum()
}

fn output(ans: u8) -> String {
    ans.to_string() + "\n"
}