You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you at this minute?

USER: I need you to book a flight ticket from DCA to LAS, please help me.

ASSISTANT: Ok, I am here to help you with that. Can I know your planned trip dates?

USER: August 16 and 18, are my planned travelling dates.

ASSISTANT: May I know your good name?

USER: Betty Mitchell here.

ASSISTANT: Do you have any other requirements?

USER: I wish to return in the morning.

ASSISTANT: Ok, please wait for a minute.

USER: Sure, I will wait.

ASSISTANT: Sorry to inform you that, there are no flights available based on your travelling dates.

USER: That's ok. Thank you.

ASSISTANT: Thank you for reaching us.