/*
TASK:sub
LANG:C++
*/
#include<iostream.h>
int main()
{ long max=0,x,n,i,y,k,br=0;
  cin>>n;
  x=n;
  while (x!=0)
  {  y=x;
	 max=0;
	 while (y!=0)
	 { k=y%10;
	   y/=10;
	   if (k>max) max=k;
	 }
	 x-=max;
	 br++;
  }
  cout<<br<<endl;
return 0;
}
