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 Go (judge verdict: Time Limit Exceeded)

package main

import (
	"fmt"
)

func main() {
	var n, x int
	var o string
	fmt.Scan(&n)

	list := make([]int, 0, n)

	for i := 0; i < n; i++ {
		fmt.Scan(&o)
		if o == "insert" {
			fmt.Scan(&x)
			list = append([]int{x}, list...)
		} else if o == "delete" {
			fmt.Scan(&x)
			index := -1
			for i, v := range list {
				if v == x {
					index = i
					break
				}
			}
			if index != -1 {
				list = append(list[:index], list[index+1:]...)
			}
		} else if o == "deleteFirst" {
			list = list[1:]
		} else {
			list = list[:len(list)-1]
		}
	}

	str := fmt.Sprint(list)
	fmt.Println(str[1:len(str)-1])
}