import java.util.Scanner;

public class Answer {
	public static void main(String str[]) {
        Scanner sc = new Scanner(System.in);

        String s = sc.nextLine();
        int sum = 0;

        for(int i=0; i<s.length(); i++) {
        	char c = s.charAt(i);
        	if(Character.isDigit(c)) {
        		sum += Character.getNumericValue(c);
        	}
        }

        System.out.println(sum);
	}
}