You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: Can you help me booking a flight ticket from IAD to AUS?

ASSISTANT: Sure, may I know your name?

USER: I am Gregory Thompson.

ASSISTANT: Thank you. May I know your travel dates?

USER: I will start on 07/14 and return on 07/16.

ASSISTANT: Ok. Please tell us your class preference.

USER: No, I am comfortable with any class.

ASSISTANT: Ok. Please be on hold for a while.

USER: Sure.

ASSISTANT: Sorry, there is no flight available on your given travel dates.

USER: No problem, thank you for the information.

ASSISTANT: You are welcome and have a nice day.