You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I serve you at this moment?

USER: I want to book a ticket from LAS to IAD to go for Cultural event.

ASSISTANT: Sure, I will help you. Please send your travelling dates.

USER: My travelling dates are Sept 25 and Sept 27.

ASSISTANT: Do you have any preferences?

USER: I prefer normal-cost airline.

ASSISTANT: May I know your name?

USER: Sure, I am Emma Miller.

ASSISTANT: Sorry, there is no flight available with your requirements.

USER: Ok, no issues. Thank you.

ASSISTANT: You are welcome, have a nice day.