You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I render you today?

USER: I need your help to book a flight from DEN to OAK.

ASSISTANT: Sure, may I know your good name?

USER: I am Nancy Turner.

ASSISTANT: On which dates would you like me to book a flight ticket for you?

USER: I want to depart on July 19 and need to return on July 21.

ASSISTANT: Do you have any specifications?

USER: I need a direct flight with an economy class which departs in the morning.

ASSISTANT: Ok, please wait for a minute.

USER: Sure.

ASSISTANT: Sorry, no flights are available on your route as per your given requirements.

USER: Ok, no problem. Thank you for checking.

ASSISTANT: Thank you for choosing us.