You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: My name is Donald White.

ASSISTANT: Do you want me to help you with anything?

USER:  I am planning to visit Denver zoo, could you book a ticket from ORD to DEN?

ASSISTANT: Sure, may I know your preferable dates please?

USER: The travel dates are from 01/14 to 01/16.

ASSISTANT: Ok, please give me a minute so that I can check the availability of flights for you.

USER: Ok fine.

ASSISTANT: I am sorry to infirm that there is no flight found.

USER: That's ok, thank you for your information.

ASSISTANT: Thank you for contacting us. Have a nice day.