You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you?

USER: I am Karen Young, can you please book a ticket from ORD to PHL?

ASSISTANT: Sure, I can help you with that. May I know your planned travel dates please?

USER: My trip dates are on Apr 19 and Apr 21.

ASSISTANT: May I know your class preference please?

USER: I do not have any class preference.

ASSISTANT: In which airlines do you prefer to travel?

USER: I am okay with any airline.

ASSISTANT: Do you have any specifications regarding departure and arrival time?

USER: I want to depart at evening time.

ASSISTANT: Ok, please let me know if you have any other specifications.

USER: I need a single connection.

ASSISTANT: Please wait a while. Sorry, no flights available for you on those dates with your given details.

USER: Ok, not a problem. Thank you.

ASSISTANT: Thank you for choosing us, have a nice day.