E_Olymp20

import java.util.Scanner;

public class Main {
    static Scanner scanner;

    public static void main(String[] args) {
        scanner = new Scanner(System.in);
        int num = scanner.nextInt();
        int count = 0;
        int sum = 0;

        for (int i = 0; i < num;){
            int cNum = num;
            while (cNum > 0){
                sum+= cNum%10;
                cNum/=10;
            }
            num-=sum;
            sum = 0;
            count+=1;
        }
        System.out.println(count);
    }
}