You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you today?

USER: I want to book a ticket from IAD to SFO. Could you book a ticket?

ASSISTANT: Sure, can you share me trip dates?

USER: Departure date is Dec, 29 and return by Dec, 31.

ASSISTANT: Do you have any connection limit?

USER: I would prefer connecting flight.

ASSISTANT: Is there any other specifications?

USER: No.

ASSISTANT: May I know your good name?

USER: My name is Gregory White.

ASSISTANT: Sorry, no flights are available in this route as per your requested dates.

USER: Thank you.

ASSISTANT: Thank you for reaching us.