/*
TASK:sub
LANG:C++
*/
#include<iostream>
using namespace std;
int n,br=0;
int choose(int n)
{
    int maxx=-1;
    while(n)
    {
            if(maxx<n%10) maxx=n%10;
            n/=10;
    }
    return maxx;
}
int main()
{
    cin>>n;
    while(n)
    {
          br++; 
            n-=choose(n);
    }
    cout<<br<<endl;
    //system("pause");
    return 0;
}
