// Trace2 Example.

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

public class D extends C
{
    private int z;

    public D(int first, int second)
    {
        super(first);
        y += first;
        z = second;
    }

    public int f( )
    {
        int s = super.f( );
        z = s;
        return y + z + 4;
    }

    public String toString( )
    {
        return super.toString( ) + z;
    }
}