You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I have planned for the trip to Detroit, can you please reserve a flight ticket from Washington?

ASSISTANT: Sure.

USER: Thank you.

ASSISTANT: Let me know your travel dates.

USER: My preferable travel dates are Dec 12 and Dec 14.

ASSISTANT: Do you have any preference?

USER: I didn't have any preferences.

ASSISTANT: Can I know your airport codes?

USER: I want to take off from the airport DCA and landing at the airport DTW.

ASSISTANT: Let me know your name.

USER: My name is Sandra Williams.

ASSISTANT: Direct flight is found with airline Delta for price 200.

USER: That's fine, please go ahead with the ticket booking.

ASSISTANT: Ticket is booked having flight number 1028.

USER: Thank you for your help in reserving my flight ticket.

ASSISTANT: Thank you.

USER: You are welcome.