import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String s = sc.next();
		int ans = 0;
		for(int i = 0 ; i < s.length() ; i++) {
			if(s.charAt(i) >= '0' && s.charAt(i) <= '9') {
				ans += s.charAt(i) - '0';
			}
		}
		System.out.println(ans);
	}
}