#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>

int main()
{
    int number = 0,sum = 0,another = 0,calc = 0;
    scanf("%d",&number);

    while (number > 0)
    {
        sum = 0;
        another = number;
        while (another > 0)
        {
            sum += another % 10;
            another /= 10;
        }
        number -= sum;
        ++calc;
    }

    printf("%d",calc);
    getchar();
}