You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I guide you for today?

USER: I am Patrick Miller. I would like to attend my friend marriage at LAS, can you please help me to book a flight ticket from IAD?

ASSISTANT: Can you please share on what dates you are willing to travel?

USER: Sure, my travel dates are Sept 04 and Sept 06.

ASSISTANT: Do you have any airline preferences?

USER: My airline preference is normal-cost.

ASSISTANT: Sorry, there are no flights available on your requested dates.

USER: That's ok, thank you for your information.

ASSISTANT: Thank you for contacting us, have a nice day.