You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you?

USER: David Green here, can you please help me in booking the ticket from SEA to DCA? As I'm planning to visit Washington.

ASSISTANT: Sure, please share your planned travel dates.

USER: Ok, my planned departure and return travel dates are 05/19 and 05/21.

ASSISTANT: Do you have any specific class preference?

USER: Yes, I need business class.

ASSISTANT: We have a direct flight in economy class, do you want me to proceed?

USER: Ok, I'll adjust with that. Please proceed for booking the ticket.

ASSISTANT: Your ticket has been confirmed in Delta airline 1019 and the price is 100.

USER: That's fine, you can proceed for booking the ticket. Thank you so much for your help.

ASSISTANT: Thank you for reaching us.