#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 rec(int number) {
    if(number == 0) {
        return 0;
    }
    if(dp[number] != -1) {
        return dp[number];
    }
    int ret = INF;
    int tmp = number;
    while(tmp > 0) {
        int digit= tmp % 10;

        if(number - digit >= 0 and digit > 0)
            ret = min(ret, rec(number - digit) + 1);
        tmp /= 10;
    }
    dp[number] = ret;
    return ret;
}
int main(){
    cin >> n;
    for(int i = 0; i <= n; ++i) {
        dp[i] = -1;
    }
    cout << rec(n) << endl;
}
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