You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, do you need any help from us?

USER: Can you please help me with booking a flight ticket from DCA to LAS?

ASSISTANT: Sure, could you please share your departure and arrival day?

USER: My travel dates are Jan 18 and 20.

ASSISTANT: Ok, could I have your name please?

USER: My name is Frank Wilson.

ASSISTANT: Ok, do you need any direct or connecting flight?

USER: I need a connecting flight.

ASSISTANT: Ok, may I know your class preference?

USER: I prefer business class.

ASSISTANT: The economy class with flight number 1000 of Frontier airline is available having fare as 200 and connection as 1, is it ok for you?

USER: You can proceed with booking.

ASSISTANT: Sorry, there is no class with your request.

USER: Ok. Thank you.

ASSISTANT: You are welcome, have a great day.