import java.util.*;

class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int s = in.nextInt();

        int ans = 0;
        for(int i = 1; i <= 9; i++) {
            int temp = (int)((s % Math.pow(10, i)) / Math.pow(10, i-1));
            // System.out.println(temp);
            if(temp != 0)
                ans += temp;
            else
                ans += 10;
        }

        System.out.println(ans);
    }
}