You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you at this moment?

USER: I am planning to celebrate my birthday at San Francisco, will you help me in booking the flight ticket from DCA to SFO?

ASSISTANT: Sure, I will help you with that. Can I have your travel dates please?

USER: My preferable journey dates are May 16 and May 18.

ASSISTANT: Ok, please let me know the timings of your journey.

USER: I would like to depart in afternoon time.

ASSISTANT: Do you prefer any specific  class to travel?

USER: I prefer economy class.

ASSISTANT: Are you looking for any connecting flight or direct flight only you want?

USER: I need a flight with single connection.

ASSISTANT: Do you  have any other specifications to get best flight for you?

USER: No, thank you for asking.

ASSISTANT: Can I have your good name please to proceed further?

USER: Myself Sharon Evans.

ASSISTANT: Ok, please wait a moment.

USER: Sure, take your own time.

ASSISTANT: Sorry Sharon Evans, no flight is available to you on your dates which can depart in afternoon time.

USER: Ok, not an issue. Thank you for your information.

ASSISTANT: Thank you for choosing  us, have a good day.