/* Cheating search function that knows that |array[i] == i|.
   |n| must be the array size and |key| the item to search for.
   |array[]| is not used.
   Returns the index in |array[]| where |key| is found,
   or |-1| if |key| is not in |array[]|. */
int
cheat_search (int array[], int n, int key)
{
  return key >= 0 && key < n ? key : -1;
}