uses graph, crt;
var d, m, i, j: integer;
begin
 d:=detect; initgraph(d, m, '');
 for i:=20 to 100 do
 begin
  cleardevice;
  for j:=1 to 30 do  circle(3*i, 200, 5*j);
  delay(20);
 end;
 closegraph;
end.