uses GraphABC; 
const
  P = 49 / 100;

procedure RRect(x, y, x1, y1: real):=Rectangle(Round(x), Round(y), Round(x1 + 1), Round(y1 + 1)); 

procedure Draw(x, y, x1, y1, n: real);
begin
  var dx := Abs((x1 - x) * P); 
  var dy := Abs((y1 - y) * P);
  
  RRect(x, y, x1, y1);
  
  if dx > 1 then 
  begin
    var xm := x - dx;
    var ym := y - dy;
    var x1p := x1 + dx;
    var y1p := y1 + dy;
    
    if n <> 1 then Draw(xm, ym, x, y, 3); 
    if n <> 2 then Draw(x1, ym, x1p, y, 4); 
    if n <> 3 then Draw(x1, y1, x1p, y1p, 1); 
    if n <> 4 then Draw(xm, y1, x, y1p, 2); 
  end; 
end;

begin
  LockDrawing();
  Draw(300, 300, 600, 600, 0);
  Redraw();
end.