Write a C++ program to implement a queue using linked lists. The program should provide the following functionality:

• Enqueue data into queue
• Dequeue data from queue
• Print data at the front
• Print data at the back
• Print the entire queue
• Check if the queue is empty
• Print the number of elements in the queue

Test your program using at least the following test cases (considering the queue includes integers):

1. Check if the queue is empty: Option F.
2. Enqueue 7 into the queue: Option A.
3. Enqueue 4 into the queue: Option A.
4. Check if the queue is empty: Option F.
5. Dequeue data form the queue.
6. Print the number of elements in the queue: Option G.
7. Enqueue 5 into the queue: Option A.
8. Print the number of elements in the queue: Option G.
9. Check if the queue is empty: Option F.
10. Print data at the front: Option C.
11. Print data at the back: Option D.
12. Print entire queue: Option E.