/*

I want to write a program that returns the last element of a linked list
of elements.  For example, last(2,4,6,8) should return 8.

But I'm going to make an intensional mistake:
*/

#include<stdio.h>
#include<stdlib.h>

struct cell
{
  int car;
  struct cell * cdr;
};

struct cell* cons(int head, struct cell* tail)
{
  struct cell* A = (struct cell*)malloc(sizeof(struct cell));
  A->car = head;  A->cdr = tail;
  return A;
}

int lastval(struct cell * M)  // written with a mistake:
{
  while (M->cdr != NULL) M = M->cdr;
  return (int)M;   // what should this really be?  (int)M?
}

int main()
{
  struct cell* M = cons(2,cons(4,cons(6,NULL)));
  printf("%d\n", lastval(M) + 4);   // give me 10 PLEASE!
}