import java.util.Scanner;

class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        String s = scan.next();
        char[] c = s.toCharArray();
        int sum = 0;
        for (int i = 0; i < c.length; i++) {
            if (Character.isDigit(c[i])) {
                sum += Character.getNumericValue(c[i]);
            }
        }
        System.out.println(sum);
        scan.close();
    }
}