---

abstract class Shape {
    double x, y;

    Shape(double x, double y) {
        this.x = x;
        this.y = y;
    }
}

class Circle extends Shape {
    Circle(double x, double y) {
        super(x, y);
    }
}

class Rectangle extends Shape {
    Rectangle(double x, double y) {
        super(x, y);
    }
}

class Triangle extends Shape {
    Triangle(double x, double y) {
        super(x, y);
    }
}

public class Main {
    static double distance(Shape a, Shape b) {
        return Math.sqrt(
            Math.pow(a.x - b.x, 2) +
            Math.pow(a.y - b.y, 2)
        );
    }

    public static void main(String[] args) {
        Circle a = new Circle(0, 0);
        Rectangle b = new Rectangle(3, 4);
        Triangle c = new Triangle(6, 8);

        System.out.println(distance(a, b));
        System.out.println(distance(b, c));
    }
}