/*
TASK:sub
LANG:C++
*/
#include <iostream>
using namespace std;
int main()
{int n,i,j=0,br=0;
cin>>n;
while(n>0)
{i=n;
while(i>0)
{if(i%10>j)
j=i%10;
i=i/10;
}
n=n-j;
br++;
}
cout<<br<<"\n";
return 0;
}
