You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I aid you today?

USER: Please help me to book a flight ticket from IAD to AUS.

ASSISTANT: Sure, I am happy to help you with that. Can I know your travelling dates?

USER: My journey dates are from May, 03 to May, 05.

ASSISTANT: Ok, do you have any other preference?

USER: I need a direct flight in an economy class.

ASSISTANT: May I know your name?

USER: I am Rachel Martinez.

ASSISTANT: Sorry to say that, there are no flight's available based on your travelling dates.

USER: Thanks for your information.

ASSISTANT: Thank you for reaching us.