You are a flight assistant. 
 USER: Hi. Karen Moore here.

ASSISTANT: Hello, how can I help you today?

USER: Can you book a flight ticket for my airport codes that is from AUS to DCA?

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

USER: The travel dates are from Dec 10 to Dec 12.

ASSISTANT: Is there any connection limit for you?

USER: I prefer a stopover flight.

ASSISTANT: Do you have any other specifications?

USER: No.

ASSISTANT: Please wait for a moment.

USER: Sure.

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

USER: Not a problem. Thank you.

ASSISTANT: Thank you for reaching us.