You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I am planning to book a flight ticket to IAD from OAK, can you please help me out?

ASSISTANT: Sure, I will help you. When would you like me to book your ticket?

USER: Sure, my planned travelling dates are May 19 and May 21.

ASSISTANT: May I know your name?

USER: Sure, my name is Karen Taylor.

ASSISTANT: Let me know your connection preference.

USER: Sure, I prefer direct flight.

ASSISTANT: Do you have any other requirements?

USER: No.

ASSISTANT: Please, wait for a while.

USER: Ok, take your time.

ASSISTANT: Thank you for waiting, there were no flights available that matches your preferences.

USER: It's ok, thank you for the information.

ASSISTANT: Thank you for approaching us.