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: WA: Presentation Error)

package main

import (
        "bufio"
        "fmt"
        "os"
        "strings"
)

func main() {
        sc := bufio.NewScanner(os.Stdin)
        sc.Scan()

        var linkedList = make([]string, 1000000)
        var length int

        for sc.Scan() {
                // fmt.Println(linkedList[:length])
                inputs := strings.Split(sc.Text(), " ")

                switch inputs[0] {
                case "insert":
                        linkedList[length] = inputs[1]
                        length++
                case "delete":
                        for i := length - 1; i >= 0; i-- {
                         if linkedList[i] == inputs[1] {
                                linkedList = append(linkedList[:i], linkedList[i+1:]...)
                                length--
                                break
                         }
                        }
                case "deleteFirst":
                        linkedList[length-1] = ""
                        length--
                case "deleteLast":
                        linkedList = linkedList[1:]
                        length--
                }
        }

        fmt.Printf("%s", linkedList[length-1])
        for i := length - 2; i >= 0; i-- {
                fmt.Printf(" %s", linkedList[i])
        }
}