#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 a){
  a->prev->next = a->next;
  a->next->prev = a->prev;
}

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(void){
  int i,N,key;

  int size = 0,np = 0, nd = 0;

  char com[20];

  scanf("%d", &N);

  init();

  for ( i = 0; i < N; i++ ){

    scanf("%s%d", com, &key);

    if(key<0 && key>2000000000){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 > 1000000 ) { printf("error"); }
  }


  if( np+nd > 2000000){printf("error") ;}
  if(nd > 20){printf("error") ;}

  printList();


  return 0;
}

