You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: I would like to book a ticket from OAK to DEN.

ASSISTANT: May I know your travel dates?

USER: Depart date is Mar, 31 and return is by Apr, 2.

ASSISTANT: Do you prefer connecting flight?

USER: I would prefer direct flight.

ASSISTANT: Do you have any other specifications?

USER: I prefer business class.

ASSISTANT: May I know your good name?

USER: My name is Eric Lopez.

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

USER: Thank you.

ASSISTANT: Thank you for reaching us.