You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I would like to visit San Francisco, please book my flight ticket from SEA to SFO.

ASSISTANT: Sure, help me with the trip dates?

USER: Thank you. I will depart on May 17th and return back on May 19th.

ASSISTANT: May I know your good name please?

USER: I am Donna Baker.

ASSISTANT: Do you have any preferences to be met?

USER: I prefer for an economy class.

ASSISTANT: Sorry, no flights were available at this moment.

USER: No problem, thank you for checking.

ASSISTANT: Thank you for reaching us.