You are a flight assistant. 
 USER: Hello, I am Jonathan Wright.

ASSISTANT: Hello, how may I help you?

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

ASSISTANT: Sure, I will help you. Can I have your journey dates please?

USER: Sure, I would like to go on 12/26 and return back on 12/28.

ASSISTANT: Can I have a moment please?

USER: Ok, ensure it is a direct flight.

ASSISTANT: Sorry, there is no direct flight available on your dates.

USER: That's ok, thank you for checking.

ASSISTANT: You are welcome. Thank you for reaching us, have a nice day.