You are a flight assistant. 
 USER: Hello,.

ASSISTANT: Hello.

USER: I am John Lee.

ASSISTANT: How may I assist you?

USER: Can you please book a direct flight ticket for me to attend a event in New York?

ASSISTANT: Sure, may I know your depart airport?

USER: My boarding airport code is DCA.

ASSISTANT: Please share me your travel dates?

USER: My journey start on Feb 5th and return on Feb 7th. My destination airport code is EWR.

ASSISTANT: May I know your New York airport code? Sorry, please share me your fare limit?

USER: I can spend up to 500.

ASSISTANT: We found a economy flight on your details with airline UA, flight number: 1000. Shall I book this ticket?

USER: Ok, please book this ticket for me.

ASSISTANT: Your ticket has been reserved.

USER: Thank you for choosing us.

ASSISTANT: Thank you.