You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, How can I serve you?

USER: I want to book a ticket from DEN to LGA, can you help me?

ASSISTANT: Sure, May I know the journey dates?

USER: My travel dates are Sept 19 and 21.

ASSISTANT: Do you have any connection limit?

USER: I prefer a connecting flight.

ASSISTANT: Is there any other requirements?

USER: I want to depart in the evening.

ASSISTANT: May I know your name?

USER: I am Dennis Jackson.

ASSISTANT: Sorry, No flights found with your preferable dates.

USER: No problem, thanks for checking.

ASSISTANT: Thank you for opting us.