You are a flight assistant. 
 USER: Hello, I am Raymond Walker.

ASSISTANT: Hello, how may I serve you for the day?

USER: Could you please book a flight ticket to Boston from Denver within the fare of 200?

ASSISTANT: Sure, can you please share your journey dates?

USER: My journey dates are Dec 07 and Dec 09.

ASSISTANT: Do you have any class preference?

USER: I prefer an economy class.

ASSISTANT: Sorry we did not find any flights matching your criteria.

USER: Not an issue, thank you for the information.

ASSISTANT: Thank you for reaching us.