You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Please help me to book a flight ticket from DEN to MSP.

ASSISTANT: Can I know your travelling dates?

USER: My travel dates are 15 to 17 of Dec.

ASSISTANT: Do you have specification?

USER: I would like to travel in business class with a connecting flight.

ASSISTANT: Can I know your name?

USER: Please book a ticket with the name of Mary Jackson.

ASSISTANT: Sorry, there is no flight with your requirement.

USER: Oh! it's ok, I will choose another source to reach my destination. Thank you.

ASSISTANT: Thank you.