You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: I want to visit Denver mountain parks in Denver, can you book a ticket for me?

ASSISTANT: Sure, please tell me your airport codes.

USER: I want to fly from DCA to DEN.

ASSISTANT: OK, may I know on which dates you need booking?

USER: My trip dates are 06/16 and 06/18.

ASSISTANT: May I know your name please?

USER: My name is Andrew Nelson.

ASSISTANT: Ok. The airline AA with flight number 1001 is available. Shall I proceed booking?

USER: Yes, please.

ASSISTANT: Ok. Your reservation is done.

USER: Thank you for booking.

ASSISTANT: Welcome.