You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Joseph Campbell.

ASSISTANT: How may I help you?

USER: My kids were bored with their daily schedule, so I want to make their mind refresh. I have decided to take a tour to Las Vegas, LAS. Can you please book a ticket from DCA?

ASSISTANT: Sure, I will help you in booking the ticket. May I know your travelling dates please?

USER: My travelling dates are May 5 and May 7.

ASSISTANT: Do you have any other specifications?

USER: Yes, my return time is afternoon.

ASSISTANT: Sorry for this inconvenience, I could not find any flight with your requirements.

USER: Ok, no issues. Thank you.

ASSISTANT: Thank you for reaching us.