import java.util.Scanner;
public class a{
    public  static void main(String[] args){
        Scanner scan  =new Scanner(System.in);
        String a =scan.nextLine(); 
        String [] o =a.split("");
        //int  n =Integer.parseInt(o);  
        int sum =0;
        for(int i=0;i<o.length;i++ ){ 
            sum +=Integer.parseInt(a.substring(i,i+1)  );
            //System.out.print(m+sum);
        }
       System.out.println(sum );
        }
    
    
}