You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, what can I do for you today?

USER: I am Jeffery Lopez. I want to book a flight ticket from DEN to OAK. Could you help me with booking?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Could you please tell me your travelling dates?

USER: My travelling dates are from 11/05 to 11/07.

ASSISTANT: Do you have any specific requirement for this journey?

USER: I need direct flight.

ASSISTANT: Sure, let me go through all your needs and get beck to you.

USER: Ok.

ASSISTANT: Sorry to inform you, we don't have any flight at this moment.

USER: That's ok, no problem. Thank you.

ASSISTANT: Thank you for contacting us.