You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you today?

USER: I need to travel San Francisco, can you please reserve flight ticket from DTW and SFO?

ASSISTANT: Sure, can you share me your travelling dates?

USER: My travelling dates are Dec,22 and Dec,24.

ASSISTANT: Do you have any airline preference?

USER: I need normal-cost airlines.

ASSISTANT: Is there any other specifications?

USER: No.

ASSISTANT: May I know your name please.

USER: Myself Christopher Adams.

ASSISTANT: Sorry, no flights are found on your travel dates.

USER: That's ok, I will choose any other source to reach my destination.

ASSISTANT: Thank you for reaching us.