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: Time Limit Exceeded)

using System;

namespace C
{
    class Cont
    {
        public void insert(ref int[] list, int key, int count)
        {
            int i;
            for (i = count; i > 0; i--)
            {
                list[i] = list[i - 1];
            }
            list[0] = key;
        }

        public void delete(ref int[] list, int key, ref int count)
        {
            int i, j, flag=0;
            for (i = 0; i < count; i++)
            {
                if (list[i] == key)
                {
                    for (j = i; j < count; j++)
                    {
                        list[j] = list[j + 1];
                    }
                    flag = 1;
                    break;
                }
            }
            if (flag==0)
            {
                count++;
            }
        }

        public void deleteFirst(ref int[] list, int count)
        {
            int i;
            for (i = 0; i < count; i++)
            {
                list[i] = list[i + 1];
            }
        }

        public void deleteLast(ref int[] list, int count)
        {
            list[count - 1] = 0;
        }
    }

    class C
    {
        static void Main(string[] args)
        {
            string input1 = Console.ReadLine();
            int n = int.Parse(input1), i, count=0;
            string[] input2 = new string[2];
            int[] list = new int[n];
            Cont cont = new Cont();
            for (i = 0; i < n; i++)
            {
                input2 = Console.ReadLine().Split(' ');
                if (input2[0]== "insert")
                {
                    cont.insert(ref list, int.Parse(input2[1]), count);
                    count++;
                }
                else if (input2[0] == "delete")
                {
                    cont.delete(ref list, int.Parse(input2[1]), ref count);
                    count--;
                }
                else if (input2[0]=="deleteFirst")
                {
                    cont.deleteFirst(ref list, count);
                    count--;
                }
                else
                {
                    cont.deleteLast(ref list, count);
                    count--;
                }
            }

            for (i = 0; i < count; i++)
            {
                if (i!=0)
                {
                    Console.Write(" ");
                }
                Console.Write(list[i]);
            }
            Console.WriteLine();
        }
    }
}