You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I want to book a ticket from HOU to LAS. Could you book a ticket?

ASSISTANT: Can I have your trip dates?

USER: Depart is by Apr, 23 and return date is Apr, 25.

ASSISTANT: Do you need any connection limit?

USER: I would prefer connecting flight.

ASSISTANT: Do you have any other specifications?

USER: I prefer business class.

ASSISTANT: May I know your name?

USER: My name is Laura Nelson.

ASSISTANT: There are no flights available on your routes.

USER: Thanks.

ASSISTANT: Thank you for opting us.