//Node Queue SLL
class Node{
    int x, y;
    Node next;

    public Node(int x, int y){
        this.x = x;
        this.y = y;
    }
}
//Clase Queue
class Queue{
    Node front,rear;

    public Queue(){
        this.front = null;
        this.rear = null;
    }

    boolean isEmpty(){
        return front==null;
    }

    void enqueue(int keyX, int KeyY){
        Node temp = new Node(keyX,KeyY);

        if(this.rear == null){
            this.front = this.rear = temp;
        }
        this.rear.next=temp;
        this.rear=temp;
    }

    Node dequeue(){
        if (this.front == null)
           return null;

        Node temp = this.front;
        this.front = this.front.next;

        if (this.front == null){
            this.rear = null;
        }

        return temp;
    }

    int[] front(){
        if(isEmpty()){
            System.out.println("Empty Queue");
        }
        int []coor = {front.x,front.y};
        return coor;
    }

    int[] rear(){
        if(this.rear==null){
            System.out.println("Empty Queue");
        }
        int[] coor = {rear.x,rear.y};
        return coor;
    }
}