You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Paul Martinez.

ASSISTANT: How may I assist you?

USER: I want to do some changes in my existing reservation. Can you help me for that?

ASSISTANT: Sure, I am happy to help you. Please wait, let me check your reservation status in our database.

USER: Thank you.

ASSISTANT: I found your reservation, may I know your travel dates?

USER: My travelling dates are Nov 12 and Nov 14.

ASSISTANT: Ok, may I know your source and destination airport codes?

USER: My travelling airport codes ORD to MSP.

ASSISTANT: Ok, do you have any preferences?

USER: I need a single connecting flight.

ASSISTANT: Sorry, I did not find any flight available on your preferred travel dates.

USER: That's ok, thank you for checking.

ASSISTANT: You are welcome and thank you for choosing us.

USER: Welcome.