You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I aid you?

USER: I want to book a ticket from DCA to SFO. Could you book a ticket?

ASSISTANT: Sure, May I know your travelling dates?

USER: Travelling dates are from Oct, 26 to Oct, 28.

ASSISTANT: Do you have any preferences?

USER: I need a direct flight.

ASSISTANT: May I know your name?

USER: My name is Dorothy Rodriguez.

ASSISTANT: Thanks for your details, there are no flights found on your data.

USER: Thanks.

ASSISTANT: Thank you.