You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: I am Dennis Mitchel. I want to book a flight ticket from DCA to OAK. Could you help me in booking?

ASSISTANT: Sure, can you please provide your preferable travel dates?

USER: My travelling dates are from Apr 05-07.

ASSISTANT: Do you have any preferences?

USER: I need a halt.

ASSISTANT: Sorry, I did not find any flights for you.

USER: That's ok, no problem. Thank you.

ASSISTANT: Thank you for reaching us.