import java.util.Scanner;

public class Main {

	static Scanner sc = new Scanner(System.in);

	public static void main(String[] args) {

		String s = sc.next();
		int ans = 0;

		for(int i = 0; i < s.length(); i++) {
			char c = s.charAt(i);
			if(Character.isDigit(c)) ans += Integer.parseInt(Character.toString(c));
		}
		
		System.out.println(ans);
    }
}