#include <iostream>
#include <vector>
#include <map>
#include <queue>
#include <string>
#include <set>
#include <algorithm>
#include <list>
using namespace std;
using ll = long long int;

int main(){
    string s;
    cin >> s;
    int answ = 0;
    while(s.size() > 1){
        //cerr << s << endl;
        sort(s.begin(), s.end());
        int i = 0;
        while(s[i] == '0'){
            ++i;
        }
        swap(s[0],s[i]);
        i = s.size() - 1;
        if(s[i] == '0'){
            while(s[i] == '0'){
                s[i] = '9';
                --i;
            }
        }
        --s[i];
        while(*s.begin() == '0'){
            s.erase(s.begin());
        }
        ++answ;
    }
    answ += atoi(s.c_str());
    cout << answ << endl;
    return 0;
}