You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Edwards Perez.

ASSISTANT: How may I guide you?

USER: I am planning to book a ticket from IAD to PHL. Can you please help me out?

ASSISTANT: Sure, can I know your preferable dates?

USER: I would like to travel on 04/05 and return back on 04/07.

ASSISTANT: I am sorry, there are no flights available.

USER: That's fine. Thanks you.

ASSISTANT: Thank you.