You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: Can you please help me in reserving the ticket DEN to IAD?

ASSISTANT: Sure, may I know your travelling dates?

USER: I would like to travel on Dec 14 and again I will return back on Dec 16.

ASSISTANT: Do you need a single connecting flight?

USER: I am planning to travel in single connection flight.

ASSISTANT: May I know your other preferences?

USER: My airline preference is normal-cost.

ASSISTANT: We found a direct flight on United airline, flight number 1025 with the fare of 200. Can I proceed?

USER: Yes, please go ahead and reserve the ticket.

ASSISTANT: May I know your name?

USER: Myself David Smith.

ASSISTANT: Your ticket has been booked.

USER: Thank you very much for reserving the ticket.

ASSISTANT: Thank you for choosing us.