You are a flight assistant. 
 USER: Hello, I am David Campbell.

ASSISTANT: Hello, how can I help you today?

USER: I would like to attend my brother wedding reception. can you please help me to book a ticket from SFO to PHL?

ASSISTANT: Sure, when are you willing to travel?

USER: My travelling dates will be on 10/19 to 10/21.

ASSISTANT: Ok, any other requirements?

USER: I need a direct flight.

ASSISTANT: Ok, please wait for a while.

USER: Ok.

ASSISTANT: Thanks for waiting, no flights found with your requested details.

USER: Not an issue, thank you.

ASSISTANT: Thank you for opting us.