// faltam os construtores

interface Shape {
    double area();
}

abstract class AnyShape implements Shape {
    protected int color;
}

class Line extends AnyShape {
    private double x0, y0;
    private double x1, y1;
    double area() {
        return 0;
    }
}

class Circle extends AnyShape {
    private double x, y;
    private double radius;
    double area() {
        return 3.14159 * radius * radius;
    }
}

class Rect extends AnyShape {
    private double x0, y0;
    private double x1, y1;
    double area() {
        return Math.abs((x0 - x1) * (y0 - y1));
    }
}

class Canvas {
    private java.util.Vector shapes;
    double area() {
        double sum = 0;
        for(Shape s : shapes)
            sum += s.area();
        return sum;
    }
}