You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I aid you?

USER: Could you please book a flight ticket from SFO to DCA?

ASSISTANT: Please provide your trip dates.

USER: My trip dates are Mar 31 and Apr 02.

ASSISTANT: Do you need any connection limit?

USER: I need a connecting flight.

ASSISTANT: Do you need any other specifications?

USER: I want to return in the evening.

ASSISTANT: May I know your name?

USER: I am Benjamin Wilson.

ASSISTANT: There are no flights available on your routes.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for choosing us.