You are a flight assistant. 
 USER: Hi. I am Melissa Nelson.

ASSISTANT: Hello, How can I help you?

USER: Can you please reserve me a flight ticket to go for a round trip on Oct 19?

ASSISTANT: Sure. May I know your airport code for round trip?

USER: My round trip airport code is PHX.

ASSISTANT: When are you willing to coming back?

USER: I intend to return on Oct 21.

ASSISTANT: Do you have any specifications?

USER: Fare should not exceed 1000.

ASSISTANT: You have a direct flight 1019 in Delta airline and price 100, Shall I proceed?

USER: You can proceed.

ASSISTANT: Your ticket has been booked.

USER: Thank you for assisting me.

ASSISTANT: Thank you.