type

  listlink = ^listcell;

  listelement = integer; {This has been assumed INTEGER for this file.}
                         {User may modify to type desired. Modify PRINT}
                         {and COMPARE when you do.}
  listcell = record
    left : listlink;
    right : listlink;
    element : listelement;
  end;

  list = listlink;

  listposition = listlink;    


function compare(e1,e2 : listelement):integer;
{+--- on entry - e1 and e2 are transfered in for a comparison
 |    on exit  - compare returns +1 iff e1 > e2
 |                                0 iff e1 = e2
 |                               -1 iff e1 < e2
 +----------------------------------------------------------------------}

begin {compare}
if e1 > e2 then compare := 1
           else if e1 < e2 then compare := -1
                           else compare := 0;
end; {compare}


procedure print(var out:text; e:listelement);
{+--- on entry - e is contained in the list and is ready for output
 |    on exit  - e has been written to the corresponding out file
 +------------------------------------------------------------------------}

begin {print}
writeln (out,e:4);
end; {print}

.