#include <iostream>

class Point {
private: 
  double x, y;

public:
  Point(double, double);
  Point();
  double getx () const;
  double gety () const;
  void move(double, double);
  double distance_to(Point) const;
};

class LineSegment {
private: 
  Point *points;
  size_t number_of_points;
public:
  LineSegment(size_t s = 10);   // Serves the role as default constructor.
  ~LineSegment();
  // ...
};

std::ostream& operator<<(std::ostream&, const Point&);