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 JavaScript (judge verdict: Time Limit Exceeded)

var input = require('fs').readFileSync('/dev/stdin', 'utf8');
var lines = input.split('\n');

lines.shift();

var q = [];
lines.forEach(function(op) {
	var arr = op.split(' ');

	if (arr[0] == 'insert') {
		tmp = q;
		q = [arr[1]];
		Array.prototype.push.apply(q, tmp);
	} else if (arr[0] == 'delete') {
		for (var i = 0; i < q.length; i++) {
			if (q[i] == arr[1]) {
				q.splice(i, 1);
				break;
			}
		}
	} else if (arr[0] == 'deleteFirst') {
		q.shift();
	} else if (arr[0] == 'deleteLast') {
		q.pop();
	}
})

console.log(q.join(' '));