You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you?

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

ASSISTANT:  To proceed further, can I have your name please?

USER: Nancy Allen.

ASSISTANT: May I know your travel dates?

USER: My travelling dates are 04 and 06 of Dec.

ASSISTANT: Please let me know if you have any other specifications.

USER: I would like to travel in business class.

ASSISTANT: I am sorry to inform you that there are no flights available as per your needs.

USER: It's ok, not a problem, thank you.

ASSISTANT: Welcome, have a good day.