use std::io;

fn main() {
    let mut s = String::new();
    io::stdin().read_line(&mut s).ok();
    let v: Vec<i32> = s.split("").map(|e| e.parse().unwrap()).collect::<Vec<i32>>();
    let mut num = 0;
    for i in v.iter(){
        num += i;
    }
    println!("{num}");
}