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: Wrong Answer)

using System;
using System.Linq;
using System.Collections.Generic;

namespace C
{
    class C
    {
        static void Main(string[] args)
        {
            var list = new List<int>();
            int n, i, number=0, j=0;
            string input, input2;
            string[] input3 = new string[2];
            input = Console.ReadLine();
            n = int.Parse(input);
            for (i = 0; i < n; i++)
            {
                input2 = Console.ReadLine();

                if (input2.Contains(' ') == true)
                {
                    input3 = input2.Split(' ');
                    input = input3[0];
                    number = int.Parse(input3[1]);
                }
                else
                {
                    input = input3[0];
                }

                if (input == "insert")
                {
                    list.Insert(0, number);
                    j++;
                }
                else if (input=="delete")
                {
                    list.Remove(number);
                    j--;
                }
                else if (input=="deleteFirst")
                {
                    list.RemoveAt(0);
                    j--;
                }
                else
                {
                    list.RemoveAt(j);
                    j--;
                }
            }

            for (i=0;i<j-1;i++)
            {
                Console.Write(list[i]+" ");
            }
            Console.WriteLine(list[j-1]);
        }
    }
}