You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How can I best serve you today?

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

ASSISTANT: Sure, can you please mention your depart and arrival dates of your journey?

USER: May, 11 and May, 13 are my travel dates.

ASSISTANT: Do you have any specifications?

USER: I need connecting flight.

ASSISTANT: Can I know your good name to proceed further?

USER: Alexander Williams here.

ASSISTANT: Sorry, no flights are available in this route as per your requested dates.

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

ASSISTANT: Thank you for choosing us.