You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. What can I do for you today?

USER: I want to meet my friend's in Washington.Can you please help me for booking the flight ticket from MA-BOS to DC-IAD?

ASSISTANT: Sure, can I know your journey dates?

USER: The planned dates are from 12/18 to 12/20.

ASSISTANT: May I know your name please?

USER: I'm Barbara Scott.

ASSISTANT: Sorry Scott, no flight available on 12/18.

USER: Ok, no problem.

ASSISTANT: Thank you for reaching us.

USER: Thank you for your information.