You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello. How can I serve you?

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

ASSISTANT: Sure. Do you have any price limit?

USER: Price limit is 500.

ASSISTANT: May I know your travelling dates?

USER: My travelling dates are from 06/17 to 06/19.

ASSISTANT: Let me know your name.

USER: My name is Ashley Walker.

ASSISTANT: Thanks for your details, Please hold on.

USER: Sure.

ASSISTANT: Thanks for waiting. There are no flights found on your data.

USER: Thanks.

ASSISTANT: Thank you.