You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you today?

USER: Amanda Williams here. I would like to meet my best friend at Las Vegas, please help me in booking a ticket from HOU to LAS.

ASSISTANT: Sure, can I know your trip dates?

USER: My planned travel dates are on Dec 17 and Dec 19.

ASSISTANT: Do you have any specifications?

USER: I need a direct flight with economy class with normal cost airlines.

ASSISTANT: Sorry, no flights are available on your desired route.

USER: Oh! That's very sad to know. Anyways, thank you for checking with availability.

ASSISTANT: Thank you for reaching us.

USER: Welcome.