You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. What can I do for you today?

USER: Please help me to book a flight ticket from LGA to OAK.

ASSISTANT: Sure, on which dates would you like to travel?

USER: My trip dates are from May, 21 to May, 23.

ASSISTANT: Ok, may I know your airline preference?

USER: I am comfortable with any airline.

ASSISTANT: Ok, help me with your class preference.

USER: I am ok with any class.

ASSISTANT: Ok, do you have any other preferences?

USER: I need a direct flight.

ASSISTANT: May I know your good name please?

USER: My name is Helen Wright.

ASSISTANT: There are no flights found on your requested dates.

USER: No problem, thanks for your information.

ASSISTANT: Thank you for reaching us.