You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

USER: I am Catherine Martin. I want to book a ticket from AUS to LAS, can you help me?

ASSISTANT: Sure, I will help you to book a flight ticket. Can you please share me your travelling dates?

USER: My travel dates are Apr 21 and Apr 23.

ASSISTANT: Please give me a moment.

USER: Sure.

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

USER: No problem, thanks for checking.

ASSISTANT: Welcome, have a nice day. Thank you for choosing us.