You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you today?

USER: Helen Carter here. Please help me out in booking the ticket from DCA to EWR.

ASSISTANT: I am here to help you out. Please provide me your trip dates.

USER: My trip dates will be 08/28 and 08/30.

ASSISTANT: Sorry Carter, there is no flight in your route.

USER: That's ok, thank you.

ASSISTANT: Thank you for reaching us.