You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I aid you today?

USER: I am looking to book a flight ticket from DCA to LAX. Can you help me for that?

ASSISTANT: Sure, I am here to help you. May I know your travel dates please?

USER: My travelling dates are Jan 15 and Jan 17.

ASSISTANT: Ok, do you have any specifications?

USER: I prefer to book a economy class.

ASSISTANT: Ok, hold on for a moment. Let me check the best available flight for you.

USER: Make sure that my depart time should be afternoon.

ASSISTANT: I found a flight for you with Frontier Airlines and it costs you 100. Shall I proceed?

USER: Ok, proceed for booking.

ASSISTANT: On whose name you would like to book this ticket?

USER: My name is Kenneth Young.

ASSISTANT: Your ticket has been booked with 1003 flight number.

USER: Thank you for booking.

ASSISTANT: Welcome, thank you for choosing us. Have a great day.

USER: Welcome.