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