/*
TASK:sub
LANG:C++
*/
#include<iostream>
using namespace std;
int n,k,m,p;
int main()
{
    cin>>n;
    while(n)
    {
            k=n;
            while(k)
            {
                    if(k%10>m)m=k%10;
                    k/=10;
            }
            n-=m;
            m=0;
            p++;
    }
    cout<<p<<endl;
    return 0;
}
