You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you?

USER: I'm Richard Green. I am planning to attend music concert at DCA, can you please help me with booking a flight ticket from BOS?

ASSISTANT: On which dates you are willing to travel?

USER: Sure, I would like to take off on 10/26 and return back on 10/28.

ASSISTANT: Please wait a while.

USER: Ok, but please make sure that the price limit does not exceed 200.

ASSISTANT: Sorry to say, there is no reservation on your desired travel dates.

USER: Ok, no issues. Thank you for the information.

ASSISTANT: Thank you for opting us.