You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I serve you today?

USER: Can you aid me in booking my flight ticket from IAD to DEN?

ASSISTANT: Sure, can you mention your travel dates?

USER: My travelling dates will be May 15th to May 17th.

ASSISTANT: May I know your connection limit?

USER: I need a direct flight.

ASSISTANT: Do you have any class preference?

USER: I prefer a economy class.

ASSISTANT: May I know your good name?

USER: I am Michael Lopez.

ASSISTANT: Do you have any other specifications to be met?

USER: No.

ASSISTANT: Please wait a minute.

USER: Sure.

ASSISTANT: Sorry to say that, there are no flights available on the routes of your journey.

USER: Its ok, thank you.

ASSISTANT: Thank you for opting us.