You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: Catherine Collins here. I want to attend a Marriage in Philadelphia. Can you please help me for booking the flight ticket?

ASSISTANT: Sure, may I know your trip dates please?

USER: My travelling dates are Aug 08 and Aug 10.

ASSISTANT: Can I know your airport codes please?

USER: My airport codes are IAD and PHL.

ASSISTANT: Ok, do you have any other requirements?

USER: I need single connecting flight.

ASSISTANT: Sorry, we regret to inform you that there is no flight available as per your request.

USER: Anyway, thanks for the information.

ASSISTANT: Most welcome.