#include <string>
#include <set>
using namespace std;



class Node {

	typedef set<Node*>::const_iterator node_iterator;

private:
	string name;
	set <Node*> neighboors;
	void add_neigboor(Node* neighboor);
	void remove_neighboor(Node* neighboor);

public:
	Node(const string& aname);
	const string get_name() const;


	node_iterator nb_begin() const {
		return neighboors.begin();
	};
	node_iterator nb_end() const {
		return neighboors.end();
	};


	friend class Graph;



};

class Graph
{

	typedef set<Node*>::const_iterator node_iterator;
	
private:
	set<Node*> nodes;
public:
	Graph() {};
	void add_node(Node* node);
	void remove_node(Node* node);
	void add_edge(Node* begin, Node* end);
	void remove_edge(Node* begin, Node* end);



	node_iterator begin() {
		return nodes.begin();
	};

	node_iterator end() {
		return nodes.end();
	};
};