You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Lisa Davis.

ASSISTANT: How may I help you?

USER: I want you to book a ticket from LAS to IAD because I need to attend my farewell pary.

ASSISTANT: Sure, may I know your dates?

USER: My travelling dates are 12/01 to 12/03.

ASSISTANT: Sorry, there are no flights have been found.

USER: No problem. Thank you for helping.

ASSISTANT: Thank you for choosing us.Have a nice day.