You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am John Roberts here.

ASSISTANT: How can I aid you now?

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

ASSISTANT: Sure, I am here to help you. May I know your travel dates please?

USER: My trip dates are Oct 6 and OCT 8 respectively.

ASSISTANT: Do you have any connection limit?

USER: Make sure that connection limit is 1.

ASSISTANT: May I know about your class preference?

USER: Sorry, I need a direct flight.

ASSISTANT: Do you have any other specifications?

USER: Make sure that I prefer for economy class.

ASSISTANT: Do you have any more specifications?

USER: No.

ASSISTANT: Ok, please wait for a while.

USER: Ok.

ASSISTANT: sorry, there are no flights found on your routes as per your specifications.

USER: No,issue. Thank you.

ASSISTANT: Thank you for choosing us.