Shared code

#include <bits/stdc++.h>

using namespace std;

#define int long long int

void solve() {
    int n;
    cin >> n;
    vector<int> dp(n + 1, INT_MAX);
    auto rec = [&](int num, const auto &self) -> int {
        if (num == 0)return 0;
        if (dp[num] != INT_MAX)return dp[num];
        vector<int> digits;
        int m = num;
        while (m) {
            if (m % 10 != 0)digits.template emplace_back(m % 10);
            m /= 10;
        }
        for (int i: digits) {
            dp[num] = min(dp[num], 1 + self(num - i, self));
        }
        return dp[num];
    };
    cout << rec(n, rec);
}


signed main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    int tc = 1;
    //cin >> tc;
    for (int i = 1; i <= tc; i++) {
        solve();
    }
    return 0;
}