program task3;

{ Вводим новый тип данных }
type
  ref = ^node;

  node = record
    key: Integer;
    left, right: ref;
  end;

  { Печать содержимого бинарного дерева }
procedure Print_Btree(w: ref; l: Integer);
var
  i: Integer;
begin
  if w <> Nil then
    with w^ do
    begin
      Print_Btree(right, l + 1);
      for i := 1 to l * 4 do
        write(' ');
      writeln(key);
      Print_Btree(left, l + 1);
    end;
end;

{ Включение вершины в дерево }
procedure insBtree(value: Integer; var tree: ref);
begin
  if tree <> Nil then
  begin
    with tree^ do
    begin
      if key > value then
      begin
        insBtree(value, left);
      end;
      if key < value then
      begin
        insBtree(value, right);
      end;
    end;
  end
  else
  begin
    New(tree);
    tree^.left := Nil;
    tree^.right := Nil;
    tree^.key := value;
  end;
end;

function createTree(): ref;
var
  tree: ref;
  value: Integer;

begin
  tree := Nil;
  writeln('Enter values');
{$I-}
  read(value);
{$I+}
  while ioresult = 0 do
  begin
    insBtree(value, tree);
{$I-}
    read(value);
{$I+}
  end;

  Result := tree;
end;

function getMin(tree: ref): ref;
begin
  if tree.left = Nil then
  begin
    Result := tree;
  end
  else
  begin
    Result := getMin(tree.left);
  end;
end;

function getMax(tree: ref): ref;
begin
  if tree.right = Nil then
  begin
    Result := tree;
  end
  else
  begin
    Result := getMax(tree.right);
  end;
end;

procedure swapMinMax(tree: ref);
var
  temp: Integer;
begin
  temp := getMin(tree).key;
  getMin(tree).key := getMax(tree).key;
  getMax(tree).key := temp;
end;

var
  value: Integer;
  tree: ref;

begin
  tree := createTree();
  writeln('Printing btree');
  Print_Btree(tree, 0);

  swapMinMax(tree);
  writeln('After swap');
  Print_Btree(tree, 0);
  read(value);

end.