You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, do you need any help from us?

USER: I am Pamela Davis. Can you please book a flight ticket from DCA to BOS?

ASSISTANT: Sure, could you please share your departure and arrival day?

USER: I would like to travel on Jan 25 and need to return on Jan 27.

ASSISTANT: Sorry, there is no flight on your requested travelling dates.

USER: It's ok,thank you for the information.

ASSISTANT: You are welcome, have a great day.