use std::*;

fn getline() -> String{
	let mut __ret=String::new();
	std::io::stdin().read_line(&mut __ret).ok();
	return __ret;
}

fn main() {
    let mut s = getline();
    let mut v = Vec::new();
    loop {
        match s.pop() {
            Some(n) => {
                let num: i32 = n as i32 - 48;
                v.push(num);
            },
            None    => {
                break
            }
        }
    }
    let res = v.iter().fold(0, |a, b| a + b);
    println!("{}", res);
}