You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you today?

USER: I want to book a flight ticket from DEN to HOU. Can you please help me in that?

ASSISTANT: Sure, please share me your trip dates.

USER: I will start my journey on Nov 12 and return on Nov 14.

ASSISTANT:  Do you need direct flight or connecting flight?

USER: I would prefer to travel in direct flight.

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

USER: Janet Walker here.

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 problem.

ASSISTANT: Thank you for opting us.

USER: Thank you for checking.