You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I guide you for today?

USER: I am Larry Harris want to visit San Francisco, can you book a ticket with price under 500?

ASSISTANT: Can you please share on what dates your willing to travel?

USER: Sure, my travelling dates will be 08/02 and 08/04.

ASSISTANT: Can you please share your source and destination airport codes?

USER: Yes, I want to fly from PHX to SFO.

ASSISTANT: Please give me a minute.

USER: Ok.

ASSISTANT: Sorry, there is no flight available at your requested dates.

USER: That's ok, thank you.

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