abstract class Shape {

int a,b;

public Shape(int aa, int bb) {a=aa; b=bb;}

abstract public double area();

}

class Rectangle extends Shape {

public Rectangle(int aa, int bb) {super(aa,bb);}

public double area() {return a*b;}

}

class Triangle extends Shape {

public Triangle(int aa, int bb) {super(aa,bb);}

public double area() {return a*b/2;}

}



public class XXK3 {

public static void main(String[] args) {

Shape x,y;

x=new Rectangle(10,20);

y=new Triangle(10,15);

System.out.println(x.area()+", "+y.area());

}

}
200.1, 75.1
200.0, 75.0