You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you today?

USER: Please book a flight ticket from DEN to IAD?

ASSISTANT: Sure, please share your planned trip dates?

USER: Sure, my journey dates are Oct 09 and Oct 11.

ASSISTANT: Do you have any specifications?

USER: I prefer a departure flight time at afternoon.

ASSISTANT: Do you have any class preference?

USER: No.

ASSISTANT: May I know your name?

USER: I am Susan Wright.

ASSISTANT: Sorry, there are no flights found with your given details.

USER: No problem, thank you for your information.

ASSISTANT: Thank you for reaching us.