import java.util.Scanner;

class NumAdd {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String str = in.next();
        int c, ans;
        ans = 0;
        for(int i = 0; i < str.length(); i++) {
            try {
                char x = str.charAt(i);
                String y = Character.toString(x);
                c = Integer.parseInt(y);
            } catch(Exception e) {
                continue;
            }
            ans += c;
        }
        System.out.println(ans);
    }
}