You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: Please help me to book a flight ticket from DCA to LAS.

ASSISTANT: Sure, please share your planned travel dates?

USER: My journey dates are from Sept, 14 to Sept, 16.

ASSISTANT: Do you have any connection limit?

USER: I need a direct flight only.

ASSISTANT: Any other preferences?

USER: No.

ASSISTANT: Can I have your name please?

USER: Patricia Taylor.

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

USER: Thank you.

ASSISTANT: Thank you for opting us.