interface Skattbar{              // Skatt p? importerte varer
	double skatt();
}

class Bil implements Skattbar {  // Bil: 100% skatt
	private String regNr;
	private double importpris;
	public Bil (String reg, double imppris) {
		regNr = reg; importpris = imppris;
	}	
	@Override
	public double skatt( ){return importpris;}
	public String nummer( ) {return regNr;}
}

class Ost  implements Skattbar {  // Ost: 277% skatt
	private double importprisPrKg;
	private double antKg;
	public Ost (double kgPris, double mengde) {
		importprisPrKg = kgPris; antKg = mengde;
	}	
	@Override
	public double skatt( ){return importprisPrKg*antKg*2.0;}
}