/*
TASK:sub
LANG:C++
*/
#include<iostream>
#include<sstream>
using namespace std;
int max_dig(int n){
    ostringstream s1;
    s1 << n;
    string s=s1.str();
    int l=s.length();
    char mn=s[0];
    for(int i=1;i<l;i++)
    if(s[i]>mn) mn=s[i];
    return mn-'0';}
int main(){
    int n;
    cin >> n;
    int br=0;
    while(n>0){
               n-=max_dig(n);
               br++;}
    cout << br << endl;
    return 0;
}
