You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you?

USER: Can you help me in booking a flight ticket from BOS to DEN?

ASSISTANT: Sure, can you share your trip dates?

USER: I want to travel on 12/13, and return on 12/15.

ASSISTANT: Do you have any preferences?

USER: I want to return in the evening time.

ASSISTANT: May I know your name?

USER: I am Eric Garcia.

ASSISTANT: Sorry, there is no flight on your given dates.

USER: Ok, no issues. Thanks for the information.

ASSISTANT: Thank you for reaching us.