You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you now?

USER: I want to attend a Seminar in Washington. Can you please help me for booking the flight ticket?

ASSISTANT: Sure, I will help you with booking.

USER: Thanks.

ASSISTANT: Can you provide me your source and destination point?

USER: My airport codes are IAD and DCA.

ASSISTANT: Please share me when you planned to travel?

USER: My travelling dates are Oct 27 and Oct 29.

ASSISTANT: Is there any other requirement related to booking?

USER: I prefer direct flight.

ASSISTANT: May I know you good name?

USER: Edward Martin.

ASSISTANT: Do you have any flight timing preference?

USER: No, I don't have any other preferences.

ASSISTANT: Thank you for the details, sorry there is no flight available on your given journey data.

USER: Anyway, thanks for the information.

ASSISTANT: Thank you for visiting us, have a nice day ahead.