#include <bits/stdc++.h>   using namespace std;   const long long mod = 1e9 + 7;   const long long N = 1e5 + 5;   long long ans = 1e18;   map<long long, bool> mp;   void solve(long long n, long long cnt) {     if (!n) {       cout << cnt;       exit(0);     }     string s = to_string(n);     sort(s.rbegin(), s.rend());     solve(n - (s[0] -  0 ), cnt + 1);   }   inline long long solve() {     long long n;     cin >> n;     solve(n, 0);     cout << ans;     return 0;   }   signed main() {     ios_base::sync_with_stdio(0);     cin.tie(NULL);     cout.tie(NULL);     long long t = 1;     solve();     return 0;   }   