#include<stdio.h>
#include<stdlib.h>
#include<string.h>

struct node{
  unsigned int key;
  struct node *next;
  struct node *prev;
};

typedef struct node *NodePointer;

NodePointer nil;

NodePointer listSearch(int key){
  NodePointer cur = nil->next;

  while(cur != nil && cur->key != key){
    cur = cur->next;
  }
  return cur;
}

void init(){
  nil = malloc(sizeof(struct node));
  nil->next = nil;
  nil->prev = nil;
}

void printList(){
  NodePointer cur = nil->next;
  int isf = 1;

  while(1){
    if(cur == nil) break;
    if(isf == 0) printf(" ");
    printf("%d",cur->key);
    cur = cur->next;
    isf = 0;
  }
  
  printf("\n");
}

void deleteNode(NodePointer t){
  t->prev->next = t->next;
  t->next->prev = t->prev;

  free(t);
}

void deleteFirst(){
  NodePointer t = nil->next;

  if(t == nil) return;

  deleteNode(t);
}

void deleteLast(){
  NodePointer t = nil->prev;

  if(t == nil) return;

  deleteNode(t);
}

void delete(int key){
  NodePointer t = listSearch(key);

  if(t == nil) return;

  deleteNode(t);
}

void insert(int key){
  NodePointer x;
  x = malloc(sizeof(struct node));
  x->key = key;
  x->next = nil->next;
  nil->next->prev = x;
  nil->next = x;
  x->prev = nil;
}

int main(){
  int key,n,i;
  int size = 0;
  char com[20];
  int np = 0,nd = 0;

  scanf("%d",&n);
  init();

  for(i = 0;i < n;i++){
    scanf("%s%d",com,&key);

    if(!(0 <= key && key <= 2000000000)){
      printf("error\n");
    }

    if(com[0] == 'i'){
      insert(key);
      np++;
      size++;
    }
    else if(com[0] == 'd'){
      if(strlen(com) > 6){
	if(com[6] == 'F'){
	  deleteFirst();
	}
	else if(com[6] == 'L'){
	  deleteLast();
	}
      }
      else{
	delete(key);
	nd++;
      }
      size--;
    }

    if(size > 1000000){
      printf("error\n");
    }
  }

  if(!(np + nd <= 2000000)){
    printf("error\n");
  }

  if(!(nd <= 20)){
    printf("error\n");
  }

  printList();

  return 0;
}

