#include <iostream>
#include <algorithm>
#include <fstream>
using namespace std;
const int MOD = 1e9 + 7;
const int INF = 2e9 + 10;
const int maxn = 1e6 + 5;
int n;
int dp[maxn];

int main(){
    cin >> n;
    for(int i = 0; i <= n; ++i) {
        dp[i] = INF;
    }
    dp[n] = 0;
    for(int number = n; number >= 0; --number) {
        int tmp = number;
        while(tmp > 0) {
            int digit = tmp % 10;
            if(number - digit >= 0) {
                dp[number - digit] = min(dp[number - digit], dp[number] + 1);
            }
            tmp /= 10;
        }
    }
    cout << dp[0] << endl;
}
//869167734
//869167734