You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I aid you today?

USER: Can you please reserve my flight ticket from BOS to SFO?

ASSISTANT: Sure, please share me your trip dates.

USER: My trip dates are Aug 22nd and Aug 24th.

ASSISTANT: For booking, we need your good name. Please mention it.

USER: Donald Green.

ASSISTANT: Do you need direct flight or connecting flight?

USER: I need a direct flight.

ASSISTANT: May I know your class preferences?

USER: I don't have any class preference.

ASSISTANT: Sorry to say that, there are no flights available on the routes of your journey.

USER: Ok, no issues. Thank you.

ASSISTANT: Thank you for reaching us.