You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, do you need any help from us?

USER: I am Jack Lee, planning to visit Las Vegas. Can you please book me a ticket from AUS to LAS?

ASSISTANT: Sure, could you please share your departure and arrival day?

USER: My preferable journey dates are from 04/05 to 04/07.

ASSISTANT: Sorry, there is no flight on your requested travelling dates.

USER: Ok, not an issue. I will find any alternate for this trip. Thank you for providing information.

ASSISTANT: You are welcome, have a great day.