import java.util.Scanner;

/*
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 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */

/**
 *
 * @author stillmen
 */
public class Tester{
    public static void main(String[]args){
        Scanner sc=new Scanner(System.in);
        QueueLL q=new QueueLL();
        int masukan=sc.nextInt();
        while(masukan!=-1){
            System.out.println(q.poll());
            System.out.println(q.peek());
            q.offer(masukan);
            masukan=sc.nextInt();
        }
    }
}

class QueueLL {
    protected MyLinkedList linkedList;

    public QueueLL(){
        linkedList=new MyLinkedList();
    }

    public boolean isEmpty(){
        if(linkedList.size()==0){
            return true;
        }
        else{
            return false;
        }
    }

    public boolean offer(Object newObj){
        linkedList.addLast(newObj);
        return true;
    }

    public Object poll(){
        if(!this.isEmpty()){
            return linkedList.removeFirst();
        }
        else{
            return null;
        }
    }

    public Object peek(){
        if(!this.isEmpty()){
            return linkedList.get(0);
        }
        else{
            return null;
        }
    }

    public int size(){
        return linkedList.size();
    }
}

class MyLinkedList{
        Node head;
        Node tail;
        int count;

        MyLinkedList(Node head){
            this.head=head;
            count++;
        }

        MyLinkedList(){
            this.head=null;
        }

        boolean empty(){
            if(head==null){
                return true;
            }
            else{
                return false;
            }
        }

        void addLast(Object info){
            Node newNode=new Node(info);
            if(head==null){
                this.head=newNode;
                this.tail=newNode;
            }
            else{
                this.tail.setNext(newNode);
                this.tail=newNode;
            }
            count++;
        }

        Object removeFirst(){
           if(head==null){
               return null;
           }
           else{
               count++;
               Node removedNode=head;
               head=head.getNext();
               if(head==null){
                   tail=null;
               }
               return removedNode.getInfo();
           }
        }

        Object peek(){
            if(head==null){
                return "Stack is empty";
            }
            else{
                return head;
            }
        }

        int size(){
            return this.count;
        }
    }

    class Node{
        Object info;
        Node next;

        Node(Object info){
            this.info=info;
        }

        Object getInfo(){
            return this.info;
        }

        void setInfo(Object info){
            this.info=info;
        }

        Node getNext(){
            return this.next;
        }

        void setNext(Node next){
            this.next=next;
        }
    }