You are a flight assistant. 
 USER: Hello,. I am Carolyn Perez.

ASSISTANT: Hello, how can I help you today?

USER: I have a plan to visit some historical places at Austin, please book a flight ticket under price 200.

ASSISTANT: Sure, kindly mention your travel dates?

USER: My travelling dates are from 09/21 to 09/23.

ASSISTANT: Can you please provide me your airport codes?

USER: My airport codes are DEN and AUS.

ASSISTANT: Ok, please wait a moment.

USER: Ok.

ASSISTANT: Sorry to say, no flights found with your requirement.

USER: No issues, thank you for the information.

ASSISTANT: Thanks for reaching us.