You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: I would like to book a ticket from DEN to JFK, can you please help me out?

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

USER: I would like to travel on these dates April 26th and 28th.

ASSISTANT: Do you have any specifications?

USER: I need a direct flight.

ASSISTANT: Do you have any other preferences?

USER: I prefer business class.

ASSISTANT: Please provide your name.

USER: Karen Evans here.

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

USER: Ok no problem, thank you for your services.

ASSISTANT: Welcome, have a great day.