/*
TASK:sub
LANG:C++
*/
#include<iostream>
using namespace std;
int main()
{
    int i,max=0,c,br=0,num=0,n;
    cin>>n;
    
    while(n>0)
    {
               c=n;
               while(c)
               {
                       i=c%10;
                       c/=10;
                       if(i>max)max=i;
               }
               n-=max;
               br++;
    }
    cout<<br<<endl;
}
                    
