import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int ans = 0;
        for (char c : sc.next().toCharArray()) {
            if (c > '0' && c <= '9') {
                ans += c - '0';
            }
        }
        System.out.println(ans);
    }
}