abstract class Figura{

protected double podst;
public Figura(double p) {

podst=p; }
public double pole() {

return wysokosc()*podstawa(); }
public final double podstawa(){

return podst; }
public abstract double wysokosc();

}

class Kwadrat extends Figura {

public Kwadrat(double a) {super(a);}
public double wysokosc() {

return podst; }
}

class Prostokat extends Figura {
protected double b;

public Prostokat(double a, double b){
super(a); this.b=b;}

public double wysokosc()
{ return b; }

}

class Romb extends Figura {
protected double alpha;

public Romb(double a, double d) {
super(a); alpha=d; }

public double wysokosc() {
return Math.sin(alpha)*podstawa(); }

}

public class Figury {

public static void main(String args[]){
Figura[] figury = new Figura[3];

figury[0] = new Kwadrat(1);
figury[1] = new Prostokat(1,1);

figury[2] = new Romb(1, Math.PI/2);

double d=0;

for (Figura f: figury)
d += f.pole();

System.out.println("Pole figur: "+d);

}
}