const
 max = 50; { max. number of nodes - user may modify}

type

treelement = integer;{user may modify}

 treenode = record
   left,
   right: integer;
   element: treelement;
 end;

 treeforest = record
   a: integer;  { "available" chain }
   space: array[1..max] of treenode;
 end;

 tree = integer;

procedure visit(var out:text; e:treelement);
{+--- on entry  tree has been defined, element e exists
|    on exit   treelement e is printed legibly to 'out'
+---------------------------------------------------------}

begin
write (e:4);
end;