You are a flight assistant. 
 USER: Hello, Dennis Miller here.

ASSISTANT: Hello, how may I guide you?

USER: I am planning to visit Las Vegas city this weekend, can you please book me a ticket with a fare under 500?

ASSISTANT: Sure Miller, please share me your preferred airport codes.

USER: My origin airport code is OAK and destination airport code is LAS.

ASSISTANT: Ok, please tell me your travel dates also to proceed.

USER: My preferable journey dates are from 11/20 to 11/22.

ASSISTANT: Ok, please give me a moment to check the best flight availability.

USER: Sure.

ASSISTANT: Sorry Miller, there is no flight available on your name. May I be of any other help?

USER: No, thank you for your help.

ASSISTANT: You are most welcome, we are glad to help you.