You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: I am planning to visit Las Vegas, will you help me in booking the flight ticket from DCA to LAS?

ASSISTANT: May I know your travelling dates?

USER: My preferable journey dates are June 08 and June 10.

ASSISTANT: Do you have any connection limit?

USER: No, thank you .

ASSISTANT: Ok, may I know your name to proceed further?

USER: Myself Ronald Hall. My depart time must be in evening.

ASSISTANT: Ok, do you have any other specifications?

USER: No, thank you for asking.

ASSISTANT: Ok, there are no current flights running with your specified dates.

USER: Ok, not an issue. Thank you for you information.

ASSISTANT: Thank you for reaching us.