You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I serve you?

USER: I am looking to book a flight ticket from IAD to DCA. Can you help me for that?

ASSISTANT: Sure, I will help you. Please send your travelling dates.

USER: My travelling dates are May 11 and May 13.

ASSISTANT: Do you have any preferences?

USER: I need a direct flight in my journey.

ASSISTANT: Sorry, there is no flight available with your requirements.

USER: That's ok, thank you for checking.

ASSISTANT: May I know your name?

USER: My name is Gregory Allen.

ASSISTANT: Thank you for reaching us.