/*
TASK:sub
LANG:C++
*/
#include<iostream>
using namespace std;
int main()
{
    int a[10],n,i,br=0;
    cin>>n;
    while(n)
    {
            int u=n,k=0;
            while(u)
            {
                    k++;
                    a[k]=u%10;
                    u/=10;
            }
            int max=0;
            for(i=1;i<=k;i++)if(a[i]>max)max=a[i];
            n=n-max;
            br++;
    }
    cout<<br<<endl;
    return 0;
}
