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 Python3 (judge verdict: Time Limit Exceeded)

n = int(input())
xlist = []
for i in range(n):
    command = list(map(str,input().split()))
    if (command[0] == 'insert'):
        x = command[1]
        if (len(xlist) == 0):
            xlist.append(int(x))
        else:
            xlist = [int(x)] + xlist
        #print(xlist)
    elif (command[0] == 'delete'):
        x = command[1]
        if (int(x) in xlist) :
            xlist.remove(int(x))
        #print(xlist)
    elif (command[0] == 'deleteFirst'):
        if (len(xlist) > 0):
            del xlist[0]
        #print(xlist)
    elif (command[0] == 'deleteLast'):
        if (len(xlist) > 0):
            del xlist[-1]
        #print(xlist)
n = len(xlist)
for i in range(n):
    if (i == n-1):
        print('{}'.format(xlist[i]), end = '')
    else:
        print('{} '.format(xlist[i]), end = '')
print()