You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I want to attend a Marriage in Las Vegas. Can you please help me for booking the flight ticket?

ASSISTANT: Sure, may I know your airport codes?

USER: My airport codes are ORD and LAS.

ASSISTANT: Do you have any preferences?

USER: I would prefer direct flight.

ASSISTANT: May I know your name please?

USER: My name is Eric Anderson.

ASSISTANT: Help me with the trip dates to book your flight ticket?

USER: My travelling dates are Oct 25 and Oct 27.

ASSISTANT: Sorry, no flights were available at this moment.

USER: Anyway, thanks for the information.

ASSISTANT: Thank you for opting us. Hope to serve you again.