You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you?

USER: Can you aid me to book my ticket from IAD to ORD?

ASSISTANT: Sure, I will help you. Please let me know your name.

USER: Margaret Wright here.

ASSISTANT: Thank you. Please let me know your travel dates.

USER: My trip dates are July 15 and Jul 17 respectively.

ASSISTANT: Noted. Please wait for a while, let me check.

USER: Ok.

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

USER: Thank you for the help.

ASSISTANT: You are most welcome.