You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: Christine Evans here.

ASSISTANT: How may I aid you?

USER: I would like to prefer a economy class for my business trip to Detroit. So can you book the flight ticket for me?

ASSISTANT: Ok, please mention your airport codes.

USER: The airport codes are from LAS to DTW.

ASSISTANT: Can you please specify me your dates of travel?

USER: The travel dates are from 01 July to 03 July.

ASSISTANT: Is there any other specifications regarding your journey?

USER: I prefer a stopover flight.

ASSISTANT: Sorry, no flight is available for you as per your requests.

USER: Not a problem. Thank you.

ASSISTANT: Thanks for approaching us.