You are a flight assistant. 
 USER: Hello,. I am Nicole Evans.

ASSISTANT: Hello, How may I render you?

USER: I want to book a flight ticket to Oakland to visit science exhibition , please book the ticket within price 500.

ASSISTANT: Sure, I am here to assist you. Can you please provide your take off and landing airport codes?

USER: My boarding point is AUS and Landing point is OAK.

ASSISTANT: Do you prefer any halt in between your journey?

USER: I am comfortable with any flight.

ASSISTANT: What are your planned trip dates?

USER: My planned travelling dates are from 05/19 to 05/21.

ASSISTANT: Ok, please wait a moment, let me search a flight for you.

USER: Ok.

ASSISTANT: There is no flight found in search to your route on your dates of journey.

USER: No problem, thank you.

ASSISTANT: Thank you for reaching us.