You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you?

USER: I am Joseph White, I am planning to meet my friend at Boston. Can you book a flight under fare of 200?

ASSISTANT: Sure, please let me know your airport codes.

USER: I will fly from WA-SEA to MA-BOS.

ASSISTANT: Could you please let me know your travelling dates?

USER: I like to travel on 03/31 and return on 04/02.

ASSISTANT: Sorry, there are no flights with your requirement.

USER: Ok, thanks for the information.

ASSISTANT: Thanks for choosing us, hope we serve you the best next time.