Problem:
Doubly Linked List

Your task is to implement a double linked list.

Write a program which performs the following operations:

insert x: insert an element with key x into the front of the list.

delete x: delete the first element which has the key of x from the list. If there is not such element, you need not do anything.

deleteFirst: delete the first element from the list.

deleteLast: delete the last element from the list.

Input

The input is given in the following format:

n

command1

command2

...

commandn

In the first line, the number of operations n is given. In the following n lines, the above mentioned operations are given in the following format:

insert x

delete x

deleteFirst

deleteLast

Output

Print all the element (key) in the list after the given operations. Two consequtive keys should be separated by a single space.

Constraints

The number of operations ≤ 2,000,000

The number of delete operations ≤ 20

0 ≤ value of a key ≤ 109

The number of elements in the list does not exceed 106

For a delete, deleteFirst or deleteLast operation, there is at least one element in the list.

Sample Input 1

7
insert 5
insert 2
insert 3
insert 1
delete 3
insert 6
delete 5

Sample Output 1

6 1 2

Sample Input 2

9
insert 5
insert 2
insert 3
insert 1
delete 3
insert 6
delete 5
deleteFirst
deleteLast

Sample Output 2

1

Solution in C++ (judge verdict: Time Limit Exceeded)

#include <iostream>
#include<string>
#include<cmath>
#include<algorithm>
#include<cctype>
#include<stdio.h>
#include<stack>
#include<stdlib.h>
#include<list>
#define LEN 100005
using namespace std;
//list実装

int main(){
    list<int> l;
    int n;
    cin>>n;
    for(int i=0;i<n;i++){
        string c;
        cin>>c;
        if(c[0]=='i'){
            int a;
            scanf("%d",&a);
            l.push_front(a);
        }else{
            if(c[6]=='F'){
                l.pop_front();
            }else if(c[6]=='L'){
                l.pop_back();
            }else{
                int a;
                scanf("%d",&a);
                for(list<int>::iterator itr=l.begin();itr!=l.end();itr++){
                    if(*itr==a){
                        l.erase(itr);
                        break;
                    }
                }
                
            }
        }
    }
    int i=0;
    for(list<int>::iterator itr=l.begin();itr!=l.end();itr++){
            if(i++)cout<<" ";
        printf("%d",*itr);
            
        }
    cout<<endl;
        
return 0;
}