You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: I am planning to celebrate my birthday in Oakland, so please book a flight ticket from DEN to OAK.

ASSISTANT: Yes, can you share me your dates of travel?

USER: My departure day is July 09, return day is July 11.

ASSISTANT: Do you have any preferences?

USER: I want direct flight.

ASSISTANT: Do you have any other specifications?

USER: No.

ASSISTANT: Give me a moment.

USER: Sure.

ASSISTANT: Sorry to inform you that there are no flights found on your requested criteria.

USER: No problem, thank you.

ASSISTANT: Can I know your name for documentation?

USER: My name is Matthew Edwards.

ASSISTANT: Thank you for contacting us.