// Trace1 Example.

// Draw the reference diagram, trace the instance
// variable changes and predict the output.

public class B extends A
{
    private int d;

    public B(int x, int y)
    {
        super(x, y);
        d = getW( ) * getH( );
    }

    public void f(int x)
    {
        d = x + 1;
        super.f(d);
    }

    public String toString( )
    {
        return super.toString( ) + "x" + d;
    }
}