You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: Can you  please book a flight ticket from DEN to LAS?

ASSISTANT: Sure, will you mention your travelling dates please?

USER: Thank you. I have  planned my travel dates as Oct 18 and Oct 20.

ASSISTANT: Do you have any preferences about flight connections?

USER: Yes, I am looking for direct flight so  please check with that.

ASSISTANT: Do you have any preferences about class?

USER: I would prefer economy class to travel.

ASSISTANT: Please mention your name.

USER: Sure, myself Patricia Young.

ASSISTANT: There is no flights found under your preferable details.

USER: Oh! It is sad to hear.  Anyway, thank you for your time.

ASSISTANT: Welcome, have a great day.