#include <iostream>
#include <stdlib.h>
using namespace std;

class Punkt{
private:
    int x, y;
public:
    Punkt(){

    }
    Punkt(int x, int y){
        this->x = x;
        this->y = y;
    }
    friend ostream& operator<<(ostream& os, Punkt& pp);
    friend istream& operator>>(istream& is, Punkt& pp);
};

ostream& operator<<(ostream& os, Punkt& pp){
    os << "{" << pp.x << ", " << pp.y << "}";
    return os;
}

istream& operator>>(istream& is, Punkt& pp){
    is >> pp.x;
    is >> pp.y;
    return is;
}

class Odcinek{
private:
    Punkt p, k;
public:
    Odcinek(Punkt p, Punkt k){
        this->p = p;
        this->k = k;
    }
    friend ostream &operator<<(ostream &os, Odcinek &od);
};

ostream &operator<<(ostream &os, Odcinek &od){
    os << od.p << " <-> " << od.k;
    return os;
}

int main(){
    Odcinek od(Punkt(10,5), Punkt(50, 20));
    cout << od;
    return 0;
}