Задача на классы(7)

#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>


using namespace std;

class Point
{
    double x, y, z;
    static int count;
public:
    Point()
    {
        x = y = z = 0;
        count++;
    }
    Point(double x, double y, double z)
    {
        count++;
        this->x = x;
        this->y = y;
        this->z = z;
    }
    int getCount()
    {
        return count;
    }
    double range()
    {
        return sqrt(x*x + y * y + z * z);
    }
    double getX()
    {
        return x;
    }
    double getY()
    {
        return y;
    }
    double getZ()
    {
        return z;
    }
    void show()
    {
        cout << x << ' ' << y << ' ' << z << "\n\n";
    }
    bool operator < (Point & a)
    {
        return (this->range() < a.range());
    }
};
int Point::count = 0;

const int MAXSIZE = 100;
int main()
{

    ifstream in("input.txt");
    Point a(1, 2, 4);
    Point b(2, 3, 5);
    Point c;
    a.show();
    b.show();
    c.show();
    cout << "created " << a.getCount() << " objects\n\n";
    if (a < b)
        cout << "a less than b\n\n";
    else
        cout << "a greater than b\n\n";
    cout << a.range();//расстояние от точки a до начала координат
}