import java.util.*;
import java.util.stream.*;
public class Main{
	public static void main(String... args){
		Scanner sc=new Scanner(System.in);
		String s=sc.next();
		int ans=0;
		for(char c:s.toCharArray()){
			if(Character.isDigit(c))ans+=(c-'0');
		}
		System.out.println(ans);
	}
}