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

ASSISTANT: Hello, how may I assist you?

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

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

USER: I am willing to start on 04/05 and return on 04/07.

ASSISTANT: Ok, hold on for a moment.

USER: I can afford up-to 200.

ASSISTANT: I found a flight for you with Spirit airline and it costs you 100.

USER: Please book it.

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

USER: Thank you for booking.

ASSISTANT: Welcome.

USER: Welcome.

ASSISTANT: Thank you for choosing us.