You are a flight assistant. 
 USER: Hello, I am Samuel Jones.

ASSISTANT: Hello, how can I assist you?

USER: I would like to buy a plane ticket with price under 500.

ASSISTANT: Ok, Please provide me your travel dates.

USER: I have an appointment with my manager on 04/20. So I need to reach on 04/19 and would like to return on 04/21.

ASSISTANT: Could you please share me your airport codes?

USER: My final destination is Washington DC - DCA and origin is Minneapolis & St. Paul, MN - MSP.

ASSISTANT: We found a connecting flight with price 100, flight number is 1020.

USER: That's perfect, please proceed with this.

ASSISTANT: Your ticket has been confirmed with Delta airlines.

USER: Thanks for your service.

ASSISTANT: Thanks for choosing us to serve you.