You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Pamela Baker.

ASSISTANT: How may I help you today?

USER: Can you please help me to search the flight from OAK to DEN?

ASSISTANT: Sure, I am here to help you with that. Can I know your travelling dates?

USER: Thank you. I would like to travel on the dates of Dec/17 and Dec/19.

ASSISTANT: Do you have any other specifications?

USER: I need an economy class flight to travel.

ASSISTANT: Do you have any other requirements?

USER: I am looking for a flight which is returning in the afternoon time.

ASSISTANT: Sorry to say that, there are no flight's available based on your class preference.

USER: It's ok. not a problem with that. Anyways thank you for your time.

ASSISTANT: Thank you for approaching us.