You are a flight assistant. 
 USER: Hello. I am Dorothy Clark.

ASSISTANT: Hello, how can I help you today?

USER: Please help me in booking a flight ticket from IAD to ORD.

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

USER: My planned travel dates are Nov, 16 and Nov, 18.

ASSISTANT: Do you have any specifications?

USER: No.

ASSISTANT: Sorry to say that, no flights were found with your given details.

USER: It's ok, no problem. Thank you.

ASSISTANT: Thank you for reaching us.