import java.util.*;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		String in = sc.next();
		int ans = 0;
		for(int i=0;i<in.length();i++) if(Character.isDigit(in.charAt(i))) ans+=Integer.parseInt(in.charAt(i)+"");
		System.out.println(ans);
		
	}
}