You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist you?

USER: I need to book a flight ticket from DEN to IAD, can you help me in booking a flight ticket?

ASSISTANT: Sure, I'm happy to help you with that. May I know your planned departure and return travel dates please?

USER: Sure, my scheduled dates are Aug 11 and Aug 13.

ASSISTANT: Do you prefer stopover in between your journey?

USER: I prefer a direct flight.

ASSISTANT: Please let me know if you have any other specifications.

USER: No more specifications.

ASSISTANT: May I know your good name please?

USER: Sure, Lisa Parker here.

ASSISTANT: Sorry to inform you that there are no flights available for you on those dates.

USER: Ok, no issues. Thank you for your information.

ASSISTANT: Thank you for choosing us.