You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am Helen Parker. Can you please help me in booking a flight ticket to IAD from OAK?

ASSISTANT: Sure, please provide your trip dates.

USER: My planned dates are from Nov 28 to Nov 30.

ASSISTANT: Ok, can you please tell me if you have any preference?

USER: Make sure that depart time should be in the morning. I need a single connecting flight.

ASSISTANT: Ok, please wait a minute.

USER: Ok.

ASSISTANT: Sorry Helen, there is no flights available in the morning.

USER: Ok, no problem.

ASSISTANT: Most welcome.

USER: Thank you.