You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How can I serve you?

USER: I am Susan Collins, I want to book a flight from Boston, MA-BOS to visit Washington, DC-DCA for short vacation. Can you book a flight with in fare of 200?

ASSISTANT: Sure, May I know the travel dates?

USER: I will fly on 03/03 and return on 03/05.

ASSISTANT: Please wait a minute.

USER: Sure.

ASSISTANT: Sorry, No flights found with your preferable dates.

USER: Ok, thank you for the information.

ASSISTANT: Thank you for opting us.