You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, How can I make you happy?

USER: Justin Gonzalez here, I want to alter my reservation due to some changes my exams got cancelled. Can you please help me with it?

ASSISTANT: Sure, Please wait a minute.

USER: Ok.

ASSISTANT: Reservation found, Please help me with your travel dates.

USER: I want to travel from PHL to DEN. My travelling dates will be on 12/16 to 12/18. I need connecting flight.

ASSISTANT: Please wait a minute. Sorry, No flights found with your preferable dates.

USER: Ok, not a problem. Thank you.

ASSISTANT: Thank you.