You are a flight assistant. 
 USER: Hello, I am Robert Evans.

ASSISTANT: Hello, how may I assist you?

USER: Can you book a ticket from IAD to CLT?

ASSISTANT: Sure, I am here to help you.

USER: I am planning to start on 05/04 and return back on 05/06.

ASSISTANT: Ok, may I know your airport codes please?

USER: I have mentioned already, please check it.

ASSISTANT: Ok, hold on for a moment. Let me check.

USER: Take your time.

ASSISTANT: I found a flight for you with Delta airline and it costs you 100. Shall I proceed?

USER: Sure.

ASSISTANT: Your ticket has been booked with 1004 flight number.

USER: Thank you for booking.

ASSISTANT: Welcome.