You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I be of your assistance?

USER: Can you help me to book a flight ticket from DEN to IAD?

ASSISTANT: Sure, we are happy to assist you in booking. May I know your name please?

USER: I am Andrew Williams.

ASSISTANT: Could you please let me know if you need a connecting flight?

USER: I prefer connecting flight.

ASSISTANT: Please share your planned travelling dates to proceed further.

USER: My trip dates are Feb 24 and Feb 26.

ASSISTANT: Is there any other preferences that you would like to add before booking?

USER: No.

ASSISTANT: Ok, please wait a moment I'll search best flight for you.

USER: Sure.

ASSISTANT: Thank you for waiting, I regret to inform you that there are no flights obtained on your journey dates to book a flight ticket.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for approaching us.