uses GraphABC;

procedure RLine(x, y, x1, y1: real) := Line(Round(x), Round(y), Round(x1), Round(y1));

procedure Draw(x, y, x1, y1, x2, y2: real; iterations: integer);
begin
  if iterations > 0 then
  begin
    var mx1 := (x + x1) / 2;
    var my1 := (y + y1) / 2;
    var mx2 := (x1 + x2) / 2;
    var my2 := (y1 + y2) / 2;
    var mx3 := (x2 + x) / 2;
    var my3 := (y2 + y) / 2;
    
    Dec(iterations);
    Draw(x, y, mx1, my1, mx3, my3, iterations);
    Draw(mx1, my1, x1, y1, mx2, my2, iterations);
    Draw(mx3, my3, mx2, my2, x2, y2, iterations);
  end
  else
  begin
    RLine(x, y, x1, y1);
    RLine(x1, y1, x2, y2);
    RLine(x2, y2, x, y);
  end;
end;

begin
  Lockdrawing();
  Draw(100, 500, 100, 100, 500, 500, 8);
  Redraw();
end.