#include <bits/stdc++.h>
using namespace std;
string s, s1;
int a[1000];
set<string> l;
void fun() {
  memset(a, 0, sizeof(a));
  int len = s.length();
  int j = 0;
  for (int i = len - 1; i >= 0; i--) {
    a[j++] = s[i] - '0';
  }
  a[0]++;
  for (int i = 0; i < len; i++) {
    if (a[i] >= 10) {
      a[i + 1] += a[i] / 10;
      a[i] %= 10;
    }
  }
  if (a[len] != 0) len++;
  int index;
  for (int i = 0; i < len; i++) {
    if (a[i] == 0) continue;
    index = i;
    break;
  }
  for (int i = len - 1; i >= index; i--) {
    s1 += a[i] + '0';
  }
}
int main() {
  while (cin >> s) {
    l.clear();
    l.insert(s);
    s1 = "";
    fun();
    int sum = 1;
    while (l.count(s1) != 1) {
      l.insert(s1);
      s = s1;
      s1 = "";
      fun();
      sum++;
    }
    cout << sum << endl;
  }
  return 0;
}
