You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I assist you today?

USER: I am Mary Lee want to visit IAD, can you book a ticket from ORD?

ASSISTANT: Ok, please share your planned dates for the following journey?

USER: Sure, my travelling dates will be 12/07 and 12/09.

ASSISTANT: Mary Lee, please wait for a moment.

USER: Ok.

ASSISTANT: Sorry to tell you, there are no flights available on your request.

USER: Ok, no issues. Thank you for checking.

ASSISTANT: Thank you for choosing our assistance. Have a nice day.