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.Text;

class Program
{
    public void Proc()
    {
        int commandCount = int.Parse(Console.ReadLine());

        long[] linear = new long[(int)Math.Min(commandCount, Math.Pow(10, 6))+1];
        int itemCount = 0;

        for(int i=0; i<commandCount; i++)
        {
            string[] inpt = Console.ReadLine().Split(' ');
            long num = 0;

            if (inpt.Length >= 2)
            {
                num = long.Parse(inpt[1]);
            }

            switch (inpt[0])
            {
                case "insert":
                    for(int j= itemCount-1; j>=0; j--)
                    {
                        linear[j + 1] = linear[j];
                    }
                    linear[0] = num;
                    itemCount++;
                    break;
                case "delete":
                    bool isFinded = false;
                    for(int j=0; j<itemCount; j++)
                    {
                        if(linear[j] == num)
                        {
                            isFinded = true;
                        }
                        if(isFinded)
                        {
                            linear[j] = linear[j + 1];
                        }
                    }
                    itemCount--;
                    break;
                case "deleteFirst":
                    for(int j=0; j<itemCount;j++)
                    {
                        linear[j] = linear[j + 1];
                    }
                    itemCount--;
                    break;
                case "deleteLast":
                    linear[itemCount - 1] = -1;
                    itemCount--;
                    break; 
            }
        }
        StringBuilder ans = new StringBuilder();
        for(int i=0; i<itemCount; i++)
        {
            if(ans.Length > 0)
            {
                ans.Append(" ");
            }
            ans.Append(linear[i]);
        }
        Console.WriteLine(ans.ToString());
        
    }

    static void Main(string[] args)

    {

        Program prg = new Program();
        prg.Proc();

    }
}