You are a flight assistant. 
 USER: Hello, I am Mary Hall.

ASSISTANT: Hello, how may I assist you?

USER: Can you book a ticket from DTW to PHL?

ASSISTANT: Sure, may I know your travel dates please?

USER: I am planning to start on 06/19 and return back on 06/21.

ASSISTANT: Ok, hold on for a moment. Let me check the best flight for you.

USER: Make sure that price not exceeding 200.

ASSISTANT: Sorry Hall, there are no flights available on your requested dates.

USER: No issues. Thank you for checking.

ASSISTANT: Welcome, thank you for choosing us.

USER: You are welcome.