import java.util.function.BiFunction;

public final class Zad3 {
    public static void main(String[] args) {

    	//Function<Integer, Integer, Integer> apply = (x, y) -> x * y;

    	BiFunction<Double, Double, Double> fun = (stawka,podstawa) -> stawka * podstawa;

    	Podatek podatek = new Podatek();

    	System.out.print(podatek.obliczPodatek(17, 1000, fun));

    }
}

@FunctionalInterface
interface IPodatek {
    double obliczPodatek(double stawka, double podstawa, BiFunction<Double, Double, Double> fun);
}

class Podatek implements IPodatek {

	@Override
	public double obliczPodatek(double stawka, double podstawa, BiFunction<Double, Double, Double> fun) {
		return fun.apply(stawka, podstawa);
	}
}