import java.util.Arrays;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Scanner;
import java.util.Set;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		int answer = 0;
		for(final char c : sc.next().toCharArray()){
			if(Character.isDigit(c)){
				answer += Character.getNumericValue(c);
			}
		}
		
		System.out.println(answer);
		
	}

}