You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: I would like to celebrate this Christmas with my family at Denver, please help me in booking a ticket from OAK to DEN.

ASSISTANT: Sure, may I know your planned travel dates please?

USER: My planned travel dates are on Dec 25 and Dec 27.

ASSISTANT: Is there any airline preference?

USER: I am fine with any airlines.

ASSISTANT: Would you like to have any lay off in your journey?

USER: Yes, I need a flight with single connection.

ASSISTANT: Do you have any particular timing for travelling?

USER: No, thank you for asking.

ASSISTANT: Do you want to fly in economy class or business class?

USER: I am comfortable with any class.

ASSISTANT: Can you please mention your name to proceed further?

USER: Sure, my name is Deborah Hill.

ASSISTANT: Please wait.

USER: Sure, please make it fast.

ASSISTANT: Thank you for waiting, but I regret to inform you that there were no flights found as per your requirement.

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

ASSISTANT: Thank you for contacting us and have a nice day.