You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I assist you today?

USER: I need to book a flight ticket from SFO to LAS to meet my friend. Can you please book a direct flight ticket?

ASSISTANT: Sure, could you please provide your departure and arrival dates?

USER: My journey dates are Mar 17 and Mar 19.

ASSISTANT: Do you have any specifications to be met?

USER: No.

ASSISTANT: Are you looking for any preferred class?

USER: I prefer a economy class.

ASSISTANT: We have found a direct flight of United airlines, flight number-1020 class-economy and fare is 100. Shall I proceed with the booking?

USER: Go ahead.

ASSISTANT: May I know your name to proceed?

USER: I am Mark Miller.

ASSISTANT: Sure, your ticket has been booked.

USER: Thank you for your help.