#include <bits/stdc++.h>
using namespace std;
 
int main() {
  int n;
  cin >> n;
  vector <int> dp(n + 1, 1e9);
  dp[0] = 0;
  for (int i = 1; i <= n; i++) {
    int x = i;
    while (x > 0) {
      int digit = x % 10;
      if (digit > 0) {
        dp[i] = min(dp[i], dp[i - digit] + 1);
      }
      x /= 10;
    }
  }
  cout << dp[n] << endl;
  return 0;
}