You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Gregory Williams.

ASSISTANT: How may I help you out?

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

ASSISTANT: Sure, I will help you in booking the ticket.

USER: Sure, my trip dates are from 03/29 to 03/31.

ASSISTANT: Sorry, there are no flights found.

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

ASSISTANT: Thank you for choosing us.