You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how best can I assist you for the day?

USER: I am looking for a direct flight from Oakland to Dallas. Can you book a flight for me?

ASSISTANT: Sure, when are you planning to start and return on?

USER: I plan to travel on Feb 27 and return on Feb 29.

ASSISTANT: Which airports do you prefer to fly and land on?

USER: My source point is OAK and my destination is DFW.

ASSISTANT: Do you prefer a connecting flight?

USER: No, I want a direct flight.

ASSISTANT: Can I know your preferences?

USER: I do not have any other preference.

ASSISTANT: Can I know your good name?

USER: My name is Nicholas Walker.

ASSISTANT: Thank yo for your details, there are no flights found with the given details.

USER: Ok, thank you for the information.

ASSISTANT: Thank you.