#include <bits/stdc++.h>
#define all(x) (x).begin(), (x).end()
#define FastIO ios::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL)
typedef long long ll;
using namespace std;
int main() {
    FastIO;
    ll i, zc, ans;
    string N;
    cin >> N;
    ans = 0;
    while(!N.empty()) {
        sort(all(N));
        zc = find_if(all(N), [](auto a) { return a != '0'; }) - N.begin();
        N = N.substr(zc, 1) + string(zc, '0') + N.substr(zc + 1);
        for(i = N.size() - 1; i >= 0; i--) {
            if(N[i] == '0')
                N[i] = '9';
            else {
                N[i]--;
                break;
            }
        }
        zc = find_if(all(N), [](auto a) { return a != '0'; }) - N.begin();
        N = N.substr(zc);
        ans++;
    }
    cout << ans << '\n';
    return 0;
}