// 2 февраль.cpp: определяет точку входа для консольного приложения.
//

#include "stdafx.h"
#include <iostream>

using namespace std;

struct Single_node {
	int val;
	Single_node *next;
};

class Single_list {
	private:
		Single_node *head;
		Single_node *tail;
	public:
		Single_list(); //+
		Single_list(int); //+
		~Single_list();
		bool empty(); //+
		void push_front(int); //+
		void pop_front(); //+
		void clear();
		int& front();//+
		int size(); //+
		void print(); //+
};

Single_list::Single_list() {
	Single_node *p = new Single_node;
	p->next = 0; tail = p; head = p;
}

Single_list::Single_list(int a) {
	Single_node *p = new Single_node;
	p->next = 0; tail = p;
	Single_node *node = new Single_node;
	node->val = a; node->next = tail; head = node;
}

Single_list::~Single_list() {
	while (head != 0) {
		Single_node *node = head;
		head = head->next;
		delete node;
	}
}

bool Single_list::empty() {
	return (tail == head);
}

void Single_list::push_front(int a) {
	Single_node *node = new Single_node;
	node->val = a; node->next = head;
	head = node;
}

void Single_list::pop_front() {
	Single_node *node = head->next;
	delete head;
	head = node;
}

void Single_list::clear() {
	while (head != tail) {
		Single_node *node = head->next;
		delete head;
		head = node;
	}
}

int& Single_list::front() {
	int &p = head->val;
	return p;
}

void Single_list::print() {
	for (Single_node *node = head; node != tail; node = node->next)
		cout << node->val << " ";
	cout << endl;
}

int Single_list::size() {
	int n = 0;
	for (Single_node *node = head; node != tail; node = node->next)
		n++;
	return n;
}

int main()
{
	Single_list list;
	for (int i = 0; i < 5; i++) {
		list.push_front(i);
		list.print();
	}
	list.front() = 9;
	while (!list.empty()) {
		list.print();
		list.pop_front();
	}
    return 0;
}