You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: I want to book a ticket from BOS to DCA to attend seminar, can you help me in booking?

ASSISTANT: Sure, may I know your travel dates please?

USER: I am departing on July 16 and return on July 18.

ASSISTANT: Any preferences you have?

USER: I prefer a flight which return in afternoon time.

ASSISTANT: Can you mention your name to proceed further?

USER: My name is Timothy Carter.

ASSISTANT: Sorry, no flights found as per your requirement.

USER: That's ok, thank you for your information.

ASSISTANT: Thank you for contacting us.