You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I aid you?

USER: I am Matthew Smith want to visit Seattle, can you book a ticket from IAD to SEA?

ASSISTANT: Sure, may I know your planned travel dates?

USER: Sure, my travelling dates will be 03/24 and 03/26.

ASSISTANT: Ok, please wait for a while.

USER: Ok.

ASSISTANT: Thank you for waiting. Here, there are no flights available for your desired dates.

USER: That's ok, thank you.

ASSISTANT: Thank you for reaching us.