uses GraphABC; 

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

procedure Draw(x, y, r, angle: real);
begin
  var angle1 := DegToRad(angle);
  var angle2 := DegToRad(angle - 90);
  
  var x2 := x + r * Cos(angle1); 
  var y2 := y + r * Sin(angle1); 
  var mx := (x + x2) / 2; 
  var my := (y + y2) / 2; 
  var r2 := r / 2; 
  var r3 := r2 * 0.8; 
  var cx := mx + r3 * Cos(angle2); 
  var cy := my + r3 * Sin(angle2);
  
  RLine(x, y, x2, y2); 
  RLine(mx, my, cx, cy);
  
  if r > 30 then 
  begin
    Draw(x, y, r2, angle); 
    Draw(mx, my, r2, angle); 
    Draw(mx, my, r3, angle - 90); 
    Draw(cx, cy, r3, angle + 90); 
  end; 
end;

begin
  SetWindowIsFixedSize(true);
  SetWindowSize(600, 600);
  ClearWindow(clBlack);
  
  SetPenColor(clCyan);
  
  LockDrawing();
  Draw(100, 500, 400, 0); 
  Draw(100, 100, 400, 90); 
  Draw(500, 500, 400, -90); 
  Draw(500, 100, 400, -180);
  Redraw();
end.