use std::{
    collections::{BTreeSet, HashMap},
    hash::Hash,
};

fn main() {
    proconio::input! {
        s: String
    }
    let a = s
        .chars()
        .filter_map(|c| c.to_digit(10))
        .fold(0, |a, b| a + b);
    println!("{a}");
}