#include <iostream>
#include <algorithm>
#include <fstream>
using namespace std;
const int MOD = 1e9 + 7;





int main(){
    int n,num=0;
    cin>>n;
    int k=n,cif=0;
    while (n>0){
        cif=0;
        for (int k=n;k>0;k=k/10){
            cif=max(cif,k%10);
        }
        n=n-cif;
        num++
    ;}
    cout<<num;
}
//869167734
//869167734