You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you today?

USER: Can you please book a flight ticket from DEN to OAK?

ASSISTANT: Sure, may I know your planned travel dates?

USER: My trip dates are 12/31 and 01/02.

ASSISTANT: May I know your connection limit?

USER: I am comfortable to travel in a single connecting flight.

ASSISTANT: Do you have any other specifications?

USER: I want to return in evening.

ASSISTANT: Please wait for a moment.

USER: Sure.

ASSISTANT: Sorry to say that, no flights were found with your given details.

USER: That's ok, thank you for your information.

ASSISTANT: May I know your good name for documentation purpose?

USER: Alexander Mitchell here.

ASSISTANT: Thank you for reaching us.