You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you now?

USER: I'm planning to attend a wedding, can you book a ticket from ORD to DEN?

ASSISTANT: Sure, I am glad to help you. May I know your planned dates?

USER: Sure, my planned departure and return travel dates are 21st and 23rd of Dec.

ASSISTANT: Ok, please specify your name.

USER: My name is Barbara Perez.

ASSISTANT: Do you prefer a connecting flight or a direct flight?

USER: I prefer single connected flight.

ASSISTANT: Is there any other intent's to say?

USER: Yes, I want to travel in economy class.

ASSISTANT: Sorry to say that, no flights are found based on your information.

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

ASSISTANT: Thank you for contacting us.