You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I help you?

USER: Brenda Green here.

ASSISTANT: Nice to meet you Brenda.

USER: Can you please reserve me a flight ticket from LAS to DCA?

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

USER: Sure, my travel dates are from Oct 31 to Nov 03.

ASSISTANT: Do you have any preferences?

USER: I would like to depart in the evening.

ASSISTANT: Thanks for waiting. But I am sorry to say that there are no flights available.

USER: Ok, no problem. Thank you for the information.

ASSISTANT: Thank you.