import java.util.Scanner;

public class No289 {
	public static void main(String[]args) {
		Scanner sc = new Scanner(System.in);

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

		for(int i=0;i<S.length();i++) {
			sum += Character.isLetter(S.charAt(i)) ?
					0:Integer.parseInt(String.valueOf(S.charAt(i)));
		}

		System.out.println(sum);

	}

}