You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you at this moment?

USER: Please book a ticket from BOS to attend Sports festival.

ASSISTANT: Sure, I am here to help you with that. Can I know your planned trip dates?

USER: My travelling dates are Oct 21 and Oct 23.

ASSISTANT: Do you have any other specifications?

USER: Yes, I prefer normal-cost airline.

ASSISTANT: May I know your destination code?

USER: My destination is Las Vegas, LAS.

ASSISTANT: May I know your name?

USER: Sure, Gregory Wright here.

ASSISTANT: Sorry to say that, there are no flight's available based on your travelling dates.

USER: Ok, no issues.

ASSISTANT: Thank you for reaching us.

USER: Thank you.