You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Paul Carter.

ASSISTANT: How can I assist you today?

USER: I am planning to visit Olympic National Park at Washington, could you please help me with booking a flight ticket from LAS to DCA?

ASSISTANT: Sure, can you please share your travel dates?

USER: I would like to take off on 12/13 and return on 12/15.

ASSISTANT: Let me check for the availability of flight.

USER: Sure, take your time.

ASSISTANT: Paul, there is no flight available at your requested dates.

USER: That's ok, I will find an another alternate way to complete my trip. Anyways, thank you for the information.

ASSISTANT: You are welcome. Thank you for contacting us, have a great day.