/*
TASK:SUB
LANG:C++
*/
#include<iostream>
using namespace std;
int m(int n)
{
 int max=-1;    
 while (n!=0)
 {
  if (n%10>max) max=n%10;
  n/=10;
 } 
 return max;  
} 
int main()
{
 int n,b=0;
 cin>>n;
 while (n!=0)
 {
  n-=m(n);
  b++;
 }    
 cout<<b<<endl; 
 return 0;
} 
