#include <bits/stdc++.h> 
 
using namespace std;  
 
typedef long long ll;  
typedef pair<int, int> ii;  
 
const int INF = 1e9;  
const ll LINF = 1e18;  
 
template<typename T>
void minimize(T& a, const T& b) {
	if (b < a) a = b; 
}
 
const int N = 1e6 + 5;  
 
int n; 
int dp[N]; // dp[i] = Số thao tác ít nhất để đưa i về 0 
 
int main() {
	ios::sync_with_stdio(false); 
	cin.tie(nullptr);  	
	cin >> n;   
 
	for (int i = 0; i <= n; i++) dp[i] = INF;  
	dp[0] = 0;  
 
	for (int i = 1; i <= n; i++) {
		for (int tmp = i; tmp > 0; tmp /= 10) {
			int digit = tmp % 10;  
			minimize(dp[i], dp[i - digit] + 1); 
		}
	}
 
	cout << dp[n]; 
}

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27