class DreiDPunkt {
private :
    double x,y,z;
public :
    DreiDPunkt();
    DreiDPunkt(double,double,double);
    bool operator<(const DreiDPunkt & P)const;
    inline double get_x() const {
	return x;
    }
    inline double get_y() const {
	return y;
    }
    inline double get_z() const {
	return z;
    }
};

std::ostream& operator<<(std::ostream& ostr, DreiDPunkt);