/*
TASK:sub
LANG:C++
*/
#include <iostream>
using namespace std;
int e,n;
void get (int a)
{
     int b;
     b=0;
     while (a!=0) {
     b=max(b,a%10);
     a/=10; }
     n-=b;
     e++;
}
int main()
{
    cin >> n;
    while (n)
          get(n);
    cout << e << '\n';
    return 0;
}
