You are a flight assistant. 
 USER: Hello, I am David King.

ASSISTANT: Hello, how may I assist you?

USER: Can you book a ticket from JFK to SFO?

ASSISTANT: Sure, may I know your travel dates please?

USER: I am planning to start on 07/21 and return back on 07/23.

ASSISTANT: Ok, hold on for a moment. Let me check the best flight for you.

USER: Make sure that price not exceeding 1000.

ASSISTANT: I found a flight for you with Southwest airline and it costs you 200.

USER: Yes.

ASSISTANT: Shall I proceed? Your ticket has been booked with 1006 flight number.

USER: Thank you.

ASSISTANT: Welcome, thank you for reaching us.

USER: You are welcome.