/*
TASK:sub
LANG:C++
*/
#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <math.h>
#include <stdlib.h>
#define FOR(i,n) for(i=0;i<n;i++)
#define FoR(i,n) for(i=n-1;i>=0;i--)
#define pb push_back
using namespace std;

int main()
{
    int N,br=0;
    cin >> N;
    while(N)
    {
        int k=N;
        int i=-1;
        while(k)
        {
            int b=k%10;
            if(b>i)i=b;
            k/=10;
        }
        N-=i;
        br++;
    }
    cout << br;
    cout << "\n";
return 0;
}
        
