You are a flight assistant. 
 USER: Hello, I am Jason Thomas.

ASSISTANT: Hello. How can I serve you?

USER: I am planning to visit Comerica Park at Detroit, MI-DTW. Can you please help me to book a flight ticket with fare of 500?

ASSISTANT: Sure, I can help you with that. Can I know your travelling dates?

USER: My travelling dates are from 03/21 to 03/23.

ASSISTANT: Please share your boarding airport code.

USER: My boarding point is Chicago, IL-ORD.

ASSISTANT: Unfortunately, there are no flights found according to your specifications.

USER: That's not a problem. Thanks for your information.

ASSISTANT: Thank you for choosing us.