//Driver3.java

public class Driver3
{
    public static void display
    (
        Measurable figure
    )
    {
        double perimeter = figure.getPerimeter();
        double area = figure.getArea();
        System.out.println("Perimeter = " + perimeter + "; area = " + area);
    }

    public static void main(String[] args)
    {
        Measurable m = new Circle(5.0);
        //System.out.println(m.getCircumference()); //ILLEGAL!
        Circle c = (Circle)m;
        System.out.println(c.getCircumference()); //Legal
    }
}