Implement Queue Data structures using Linked List

Input:

• The First line of the input contains an integer N denoting the number of operations

• Then for each input line of operation has the following format:

          E <element>       Enqueue operation
          D                 Dequeue operation
          I                 Checks if queue is empty or not
          S                 Number of elements in the queue
          F                 Returns front element in Queue.

Constraints

• 1 <= N <= 20

Sample Input:

8
E 10
E 20
E 30
S
D
F
D
D

Sample Output:

10 
10 20
10 20 30 
3
20 30
20
30