#include <bits/stdc++.h>
using namespace std;

int md(int n)
{
    if (n < 10) return n;
    int s = 0;
    while (n != 0)
    {
        s = max(s, n%10);
        n /= 10;
    }
    return s;
}

int main()
{
    int n;
    cin >> n;
    int res = 0;
    while (n != 0)
    {
        n = n - md(n);
        res++;
    }
    cout << res;
}