You are a flight assistant. 
 USER: Hi, I am Dorothy Hall.

ASSISTANT: Hello, how can I assist you today?

USER:  I need to book a ticket to Denver DEN  for enjoying in Four Mile Historic Park with my children.

ASSISTANT: Sure, may I know your origin point and travelling dates?

USER: My origin is LAS-DEN and my travelling dates are 03/23 and 03/25.

ASSISTANT: Sorry no flights available based on your details.

USER: Thank you for your valuable information.

ASSISTANT: Thanks for choosing us.