You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you?

USER: Please book me a ticket from OAK to DEN to meet my friends.

ASSISTANT: Sure, I can help you. Can I know your travelling dates?

USER: I have planned to travel on Mar 09th and return on 11th.

ASSISTANT: May I know your name?

USER: Myself Kathleen Collins.

ASSISTANT: Are you okay with a direct flight?

USER: Yes.

ASSISTANT: Do you have any other specifications?

USER: I like normal cost airline with economy class.

ASSISTANT: Ok. Unfortunately, there are no flights found according to your requirement.

USER: Ok, no problem. Thank you.

ASSISTANT: Thank you for picking us.