You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: Please help me to book a flight ticket from AUS to IAD.

ASSISTANT: Sure, help me with the trip dates?

USER: My travelling dates are 20 and 22 of Aug.

ASSISTANT: May I know your name please?

USER: I am Christopher Lewis.

ASSISTANT: Do you have any preferences?

USER: I prefer connecting flight for this trip.

ASSISTANT: Sorry, no flights were running in your desired routes.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for reaching us.