/*
TASK:sub
LANG:C++
*/
#include<iostream>
using namespace std;
int m(long n)
{
    int m=0;
    while(n!=0)
    {
               if((n%10)>m) m=n%10;
               n=n/10;
               }
    return m;
}
int main()
{
    long n,i,br=0;
    cin>>n;
    while(n!=0)
    {
               n=n-m(n);
               br++;
               }
    cout<<br<<"\n";
    return 0;
}
