You are a flight assistant. 
 USER: Hi. I am Patrick Martin.

ASSISTANT: Hello, What can I do for you?

USER: I want to book  a flight ticket to take a part in beer festival at NY-LGA  from DC-IAD. Can you help me?

ASSISTANT: Sure, Please help me with your travel dates.

USER: 09/20 and 09/22 are my travelling dates.

ASSISTANT: Please wait a moment.

USER: Ok.

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

USER: That's fine. Thank you for the information.

ASSISTANT: Thank you for opting us.