#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#define MAX1 1000000000 
#define MAX2 1000000
#define MAX3 2000000

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

typedef struct node*NodePointer;

NodePointer nil;

void insert(int);
void delete(int);
void deleteFirst(void);
void deleteLast(void);
NodePointer listSearch(int);
void init(void);
void printList(void);
void deleteNode(NodePointer );

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>=MAX1){
      printf("error");
    }
    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>MAX2){
      printf("error"); 
    }
  }

  if(!( np+nd <= MAX3)){
    printf("error");
  }
  if(!( nd <= 20)){
    printf("error");
  }
  printList();

  return 0;
}

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;
}

void delete(int key){
  NodePointer t = listSearch(key);
  if ( t == nil ) return;
  deleteNode(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);
}

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);
}