#ifndef QUEUE
#define QUEUE 1

template <class Item>
class Queue
{
private:
    
    struct Node
    {
	Item data;
	Node *next;
    };
    
    Node *pre_front;
    Node *rear;
    int length;
    
public:
    
    Queue ()
    {
	pre_front = new Node;
	rear = pre_front;
	length = 0;
    }
    
    ~Queue ()
    {
	Node *temp;
	temp = pre_front;
	while (temp != rear)
	{
	    pre_front = pre_front->next;
	    delete temp;
	    temp = pre_front;
	}
	delete temp;    
    }
	
    void Enqueue (Item& x)
    {
	Node *temp;
	temp = new Node;
	temp->data = x;
	rear->next = temp;
	rear = temp;
	length++;
    }

    void Dequeue (Item& x)
    {
	Node *temp;
	temp = pre_front;
	x = pre_front->next->data;
	pre_front = pre_front->next;
	delete temp;
	length--;
    }
	
    int Length ()
    {
	return length;
    }
	
};

#endif // QUEUE