You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I assist you today?

USER: I need to book a flight ticket from DTW to SFO, can you help me in booking a flight ticket?

ASSISTANT: Sure, may I know your travelling dates?

USER: Sure, my journey dates are Dec 19 and Dec 21.

ASSISTANT: Do you have any connection limit?

USER: I prefer maximum one connection.

ASSISTANT: Any other requirements to be met?

USER: I would prefer return time at afternoon. And I want to fly in a economy class.

ASSISTANT: May I know your name?

USER: Sure, Ronald Allen here.

ASSISTANT: Sorry, there are no flights found with your given details.

USER: Ok, no issues. Thank you.

ASSISTANT: Thank you for reaching us.