You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you?

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

ASSISTANT: Sure, please share your journey dates?

USER: My trip dates are 06/16 and 06/18.

ASSISTANT: Do you have any specifications?

USER: I need a connecting flight. I prefer to return in evening time.

ASSISTANT: May I know your good name?

USER: Sure, Gary Wright here.

ASSISTANT: Is there any class preferences?

USER: No.

ASSISTANT: Sorry, no flights found on your given details.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for choosing us.