You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: Can you help me to book a flight ticket from DCA to LAS?

ASSISTANT: Sure, may I know the travelling dates?

USER: My travel dates are Jan, 19 and Jan, 21.

ASSISTANT: Do you have any connection limit?

USER: I would prefer single connection.

ASSISTANT: May I know your name?

USER: Rachel Roberts here.

ASSISTANT: Sorry, no flights found with your chosen dates.

USER: Not a problem, thank you for the information.

ASSISTANT: Thank you for opting us.