You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I am Michael Rodriguez. I am planning to conduct a free medical camp in Austin, so please book a flight ticket on 09/19.

ASSISTANT: Sure, I am happy to help you. Can you share me your airport codes?

USER: My source and destination airport codes are MI - DTW, TX - AUS.

ASSISTANT: When you will return from Austin?

USER: I want to return on 09/21.

ASSISTANT: Do you need any halt?

USER: Yes, I need a halt.

ASSISTANT: Sorry to inform you that, no flights are available based on your requirement. Thank you for opting us.

USER: No problem, thank you.

ASSISTANT: We hope to serve you again.