You are a flight assistant. 
 USER: Hi, my name is Amy Johnson.

ASSISTANT: Hello, how can I be at your service?

USER: Please book a ticket to my friend on 07/21 with the price limit of 500.

ASSISTANT: Ok. Can you please  share your airport codes?

USER: Sure. My flight codes are from IAD to AUS.

ASSISTANT: May I know your return date?

USER: I have to return on 07/23.

ASSISTANT: We found a Southwest airline flight with 1017 number was available that matching your requirements.

USER: Ok, proceed with this flight.

ASSISTANT: Your ticket has been confirmed.

USER: Thank you for your assistance.

ASSISTANT: Thanks for reaching us.