import java.io.*;
 import java.util.Scanner;
 // Class for Doubly Linked List
 public class DoublyLinkedList {

// class for Node
 class Node {
 int data;
 Node prev;
 Node next;

// Constructor to create a new node with given data d
 // next and prev is by default initialized as null
 Node(int d) { data = d; }
 }
 Node head;
 Node tail;
 int size;

// Inserting node at the front of the list
 public void insertFirst(int data)
 {
 Node node = new Node(data);

if(head==null){
 tail = node;
 }
 else{
 head.prev = node;
 }
 node.next = head;
 head = node;
 size++;
 }
 // Inserting at node at the end of the list
 void insertLast(int data)
 {
 Node node = new Node(data);

if(head==null){
 head = node;
 }
 else{
 tail.next = node;
 node.prev = tail;
 }
 tail = node;

size++;
 }

public int deleteFirst(){

if(head == null){
 throw new RuntimeException("List is empty");
 }
 int temp = head.data;
 if(head.next == null){
 tail = null;
 }
 else{

head.next.prev = null;
 }
 head = head.next;
 size--;
 return temp;
 }

public int deleteLast(){
 if(tail == null){
 throw new RuntimeException("List is empty");
 }
 Node last = tail;
 if(head.next == null){
 head = null;
 }
 else{

tail.prev.next = null;
 }
 tail = tail.prev;
 size--;
 return last.data;
 }

public void printList()
 {

Node node = head;

while (node != null) {
 System.out.print(node.data + " ");
 node = node.next;
 }
 System.out.println();

}

public void insertAfter(Node current, int data)
 {

if (current == null) {
 System.out.println("The node cannot be NULL ");
 return;
 }

Node new_node = new Node(data);

new_node.next = current.next;
 current.next = new_node;
 new_node.prev = current;
 if (new_node.next != null)
 new_node.next.prev = new_node;
 size++;
 }

public int deleteAt(Node current)
 {

if (head == null || current == null) {
 throw new RuntimeException("Empty Node");
 }
 int temp = current.data;

if (head == current) {
 head = current.next;
 }

if (current.next != null) {
 current.next.prev = current.prev;
 }

if (current.prev != null) {
 current.prev.next = current.next;
 }
 size--;
 return temp;
 }
 public static void main(String[] args)throws Exception
 {

DoublyLinkedList dll = new DoublyLinkedList();

FileInputStream fis=new FileInputStream("/home/prasanna/Downloads/str.txt");
 Scanner sc=new Scanner(fis); //file to be scanned
 int count = Integer.parseInt(sc.nextLine()); //
 for (int i=0; i<count; i++) {
 String[] line = sc.nextLine().trim().split(" "); /*split the rows with space and storing*/
 if(line.length>1){
 int data = Integer.parseInt(line[1]);

if(line[0].equals("INSF")){

dll.insertFirst(data);
 }

if(line[0].equals("INSL")){
 dll.insertLast(data);
 }
 }
 if(line[0].equals("DELF")){

dll.deleteFirst();
 }
 if(line[0].equals("DELL")){

dll.deleteLast();
 }
 if(line[0].equals("PRIN")){

dll.printList();
 }

}
 sc.close(); //closes the scanner

}
 }