Based on the compareTo method for Circle objects defined in Section 6.1, what is the output of the following code sequence?

Circle c1 = new Circle(5);

Circle c2 = new Circle(5);

Circle c3 = new Circle(15);

System.out.println(c1.compareTo(c1));

System.out.println(c1.compareTo(c2));

System.out.println(c2.compareTo(c3));

System.out.println(c3.compareTo(c2));