import java.util.Scanner;

public class Main{
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        String s = sc.nextLine();
        int ans = 0;
        for(int i = 0; i < s.length(); i++){
            if(s.charAt(i) >= '0' && s.charAt(i) <= '9'){
                ans += s.charAt(i) - '0';
            }
        }
        System.out.println(ans);
    }
}