import java.lang.reflect.Array;
import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        String line = scan.nextLine();
        int counter =0;
        line = line.replace("-","");
        line = line.replace(".","");
        int [] array = new int[line.length()];
        for (int i = 0; i <array.length ; i++) {
            array[i]= Character.getNumericValue(line.charAt(i));
        }
        for (int j = 0; j <array.length ; j++) {
            counter = counter + array[j];
            if(counter>9){
                counter=counter/10+counter%10;
            }
        }
        System.out.println(counter);
    }
}