You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you today?

USER: Can you  please book a flight ticket from DEN to DCA?

ASSISTANT: Sure, can I know your trip dates?

USER: Thank you. I have  planned my travel  dates as Apr 09 and Apr 11.

ASSISTANT: Do you have any specifications?

USER: I am  looking for single connecting flight.

ASSISTANT: Can I know your good name?

USER: Sure, myself Cynthia Davis.

ASSISTANT: Sorry, no flights are available in this route as per your requested dates.

USER: Oh! It is sad to  hear. Anyway, thank you for your time.

ASSISTANT: Thank you for reaching us.

USER: Most welcome.