c1=circle(r=150,fill="purple",stroke="none") c2=circle(r=130,fill="blue",stroke="none") c3=circle(r=110,fill="turquoise",stroke="none") c4=circle(r=90,fill="green",stroke="none") c5=circle(r=70,fill="yellow",stroke="none") c6=circle(r=50,fill="orange",stroke="none") c7=circle(r=30,fill="red",stroke="none") c8=circle(r=10,fill="white",stroke="white") show(c1,c2,c3,c4,c5,c6,c7,c8)