You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

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

ASSISTANT: Sure, let me know your travelling dates.

USER: I am planning to travel on Nov 19 and return back on Nov 21.

ASSISTANT: May I know your connection limit?

USER: I am looking for a connecting flight.

ASSISTANT: Do you have any other requirements?

USER: No.

ASSISTANT: May I know your name please?

USER: My name is David Harris.

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

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

ASSISTANT: Thank you for opting us.