/*
TASK:SUB
LANG:C++
*/
#include<iostream>
using namespace std;
int main()
{
    int n,a,cif[7],c=1,l,br=0,i,m;
    cin>>n;
    while(n){
        l=n;
        c=0;
        m=-1;
        while(l){c++;cif[c]=l%10;l/=10;}
        //cout<<c<<" "<<cif[c];system("pause");
        for(i=1;i<=c;i++){if(cif[i]>m)m=cif[i];}
        //cout<<m<<" ";system("pause");
        n-=m;
        br++;
    }
    cout<<br<<"\n";
    //system("pause");
    return 0;
}
