import java.util.Scanner;

public class Tas {

	public static void main(String[] args) {
		Scanner s = new Scanner(System.in);
		char[] c = s.nextLine().toCharArray();
		s.close();
		int total = 0;
		
		for(char c2 : c){
			if(Character.isDigit(c2)){
				total += Character.getNumericValue(c2);
			}
		}
		
		System.out.println(total);

	}

}