You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Carol Allen.

ASSISTANT: How may I serve you?

USER: Reserve a direct flight from Austin, AUS to Philadelphia, PHL under 500 price range.

ASSISTANT: Sure, help me with the trip dates?

USER: Ok, my trip dates are as 09/15 and 09/17.

ASSISTANT: There are no flights running in your preferred dates.

USER: Ok, that's not a big problem. Thank you for the information.

ASSISTANT: Thank you for reaching us. Have a nice day.