#include <iostream>

using namespace std;

class Node {
	friend ostream &operator<< (ostream&, const Node*);
public:
	int data;
	Node* next;
};

ostream &operator<< (ostream& output, const Node* cur)
{
	output << " [ " << cur->data << " ] -> ";

	if (cur->next == NULL)
		output << "||";

	return output;
}

class List {
	friend ostream &operator<< (ostream&, const List&);
public:
	List(void);
	~List();
	void Add(int);
	void Delete(int);
private:
	Node* head;
	void DeleteHelper(Node*&, int);
};

List::List(void)
{
	head = NULL;
}

List::~List()
{
	Node* t;

	while (head != NULL) {
		t = head;
		head = head->next;
		delete t;
	}
}

void List::Add(int i)
{
	Node* t;

	t = new Node;
	t->data = i;
	t->next = head;
	head = t;
}

void List::Delete(int i)
{
	DeleteHelper(head, i);
}

void List::DeleteHelper(Node* &n, int i)
{
	Node* t;
	if (n != NULL) {
		if (n->data == i) {
			t = n;
			n = n->next;
			delete t;
		}
		else 
			DeleteHelper(n->next, i);
	}
}

ostream &operator<< (ostream& output, const List& c)
{
	Node* t;
	t = c.head;

	while ( t != NULL) {
		output << t;
		t = t->next;
	}

	output << endl;

	return output;
}

void main (void)
{
	List l;

	l.Add(42);
	cout << l;

	l.Add(31);
	cout << l;

	l.Add(59);
	cout << l;

	l.Delete(31);
	cout << l;

	l.Delete(60);
	cout << l;
}