You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello. How can I help you out?

USER: I am David Brown and I want to book a ticket.

ASSISTANT: Could you please let me know your source and the destination?

USER: Sure, I would like to travel from Detroit, MI-DTW to Denver, CO-DEN.

ASSISTANT: May I know your traveling dates?

USER: My journey dates are from Dec 10 to Dec 12.

ASSISTANT: Please wait a while I will get you back.

USER: OK.

ASSISTANT: Do you have any other requirements?

USER: I need direct flight with a price:500.

ASSISTANT: Thank you for being patient, there is a flight that matches your requirement.

USER: OK, Thank you for your service.

ASSISTANT: Sorry, there is a flight with 1 connection.

USER: OK.

ASSISTANT: Thank you for contacting us.