randomize
alt=1
line color (0)
Do
   Do k=1,11
      rr=random(44)+44
      xx=random(640)
      yy=random(480)
      Do r=rr,1,-11
         alt=10-alt
         solid color (random(6)+alt)
         filled circle (xx, yy, r)
         read quit key (-1)
      Loop r
   Loop k
Loop