You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello, how may I assist you?

USER: Please book a ticket from Boston, MA-BOS to Washington DC-DCA.

ASSISTANT: Sure, can you please let me know your travelling dates?

USER: Departure date is 12/03 and 12/05 is return date.

ASSISTANT: Do you prefer any halt in between journey?

USER: Please provide a halt.

ASSISTANT: May I know your name?

USER: I am Nancy Brown.

ASSISTANT: Thank you for providing your details, please wait for a while. Thank you for waiting, we are sorry to inform you that, no flights were found based on your preferred dates.

USER: Thank you.

ASSISTANT: Thank you.