You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you?

USER: I am planning to book a ticket from DCA to SFO. Can you please help me out?

ASSISTANT: May I know your trip dates please?

USER: I am planning to travel on May 29 and return back on May 31.

ASSISTANT: Do you have any connecting limit preferences?

USER: I am looking for a connecting flight.

ASSISTANT: Is there any other concern?

USER: No..

ASSISTANT: May I know your name please?

USER: My name is Ryan Wilson.

ASSISTANT: No flights found as per your preferences.

USER: That's fine, thank you for your service.

ASSISTANT: Thank you for choosing us.