You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you?

USER: I need to book a flight ticket from DCA to SFO, can you help me in booking a flight ticket?

ASSISTANT: Sure, please share your journey dates?

USER: Sure, my journey dates are Jul 28 and Jul 30.

ASSISTANT: Do you have any specifications?

USER: I prefer a direct flight.

ASSISTANT: Is there any class preference?

USER: No.

ASSISTANT: May I know your good name?

USER: Sure, Ruth Adams here.

ASSISTANT: Sorry, no flights found on your given details.

USER: Ok, no issues. Thank you for your information.

ASSISTANT: Thank you for choosing us.