You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: Can you please help me to book a flight ticket from DCA to DTW?

ASSISTANT: Let me know your travelling dates.

USER: My travelling dates are Dec 28 to Dec 30.

ASSISTANT: Do you have any preference?

USER: I need a direct flight.

ASSISTANT: Let me know your name.

USER: My name is Shirley Martin.

ASSISTANT: Sorry, no flights found for your travelling dates. Thank you.

USER: No problem, thanks for your information.