You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you?

USER: I would like to visit Denver Zoo, please help me in booking a ticket from ORD to DEN.

ASSISTANT: Sure, can you share your trip dates?

USER: My planned trip dates are on July 22 and July 24.

ASSISTANT: Do you have any preferences?

USER: I would like to return in the evening.

ASSISTANT: May I know your name?

USER: My name is Amy Clark.

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

USER: Ok, no problem. Thank you for your information.

ASSISTANT: Thank you for reaching us.