You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you?

USER: Myself Andrew Nelson.

ASSISTANT: Hi Nelson.

USER: I want to travel from  BOS to DCA to attend seminar, please help me for booking flight ticket.

ASSISTANT: May I know your preferable dates of travelling?

USER: My travelling dates from 06/16 to 06/18. Make sure that connection limit is 1 and price limit is 200.

ASSISTANT: Sorry to inform you that there is no flight matching with your requested dates.

USER: Ok,. Thank you.

ASSISTANT: Thank you for choosing our service, have a nice day.