// ~/.vim/cpp_template.cpp
#include <bits/stdc++.h>
#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#define REP(i,a,b) for (int i = a; i < b; i++)
// Type Aliases for 1D and 2D vectors with initialization
#define vi(n, val) vector<int>(n, val) // 1D vector of ints with size n, initialized to val
#define vll(n, val) vector<long long>(n, val) // 1D vector of long longs with size n, initialized to val
#define ll long long
#define vvi(n, m, val) vector<vector<int>>(n, vector<int>(m, val)) // 2D vector of ints (n x m), initialized to val
#define vvll(n, m, val) vector<vector<long long>>(n, vector<long long>(m, val)) // 2D vector of long longs (n x m), initialized to val
using namespace std;
template <typename T>
void pV(const std::vector<T>& vec, const std::string& label = "Vector") {
std::cout << label << ": [ ";
for (const auto& elem : vec) {
std::cout << elem << " ";
}
std::cout << "]" << std::endl;
}
using namespace std;
void dfs(int s, vector<bool> *visited, vector<int> (*adj)[]) {
if ((*visited)[s]) return;
(*visited)[s] = true;
// process node s
for (auto u: (*adj)[s]) {
dfs(u, visited, adj);
}
}
/*
vector<int> adj[N];
vector<bool> visited(N, false);
int u, v;
for(int i = 0; i < M;i++){
cin >> u >> v;
u--;
v--;
adj[u].push_back(v);
adj[v].push_back(u);
}
*/
int maxNo(int x){
int mx = 0;
while(x > 0){
mx = max(mx, x % 10);
x/= 10;
}
return mx;
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
// Your code starts here
int n;
cin >> n;
int res = 0;
while(n > 0){
n-= maxNo(n);
res++;
}
cout << res << endl;
return 0;
}
