You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How can I respond to your request?

USER: Mary Parker here. I want to book a flight ticket from DTW to SFO. Can you help me in that?

ASSISTANT: Sure, we are perky to assist you.

USER: Thank you.

ASSISTANT: May I know on which dates you are planning to start and return?

USER: My trip dates are Sept 3 to Sept 5.

ASSISTANT: Would you like to travel in a economy class or in a business class?

USER: I am okay with any class.

ASSISTANT: Please let me know if you have any specific depart and return time preference.

USER: My depart time should be in the afternoon.

ASSISTANT: Do you need any whistle stop in between journey?

USER: I need a connecting flight.

ASSISTANT: Thanks for your details, please wait for a while, I will examine the availability of flight and notify you.

USER: Sure.

ASSISTANT: Thank you for waiting, sorry to inform you that unfortunately there is no flights available by the given details.

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

ASSISTANT: Thanks for contacting with us, wish you a nice day.