You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you today?

USER: Could you please help me to book a direct flight from Seattle to visit Central Hall in Philadelphia?

ASSISTANT: Sure, may I know your desired airport codes?

USER: My boarding airport code is SEA and my destination airport code is PHL.

ASSISTANT: Can you please share your trip dates?

USER: I want to reach PA on Apr 10th and my return date will be on Apr 12th.

ASSISTANT: Is there any class preference?

USER: No, I don't have any other preference.

ASSISTANT: May I know your good name?

USER: I am Jennifer Wright.

ASSISTANT: Sorry, there are no flights found on your specified trip dates.

USER: That's fine, I'll choose any alternative to reach my destination. Thank you for your information.

ASSISTANT: Thank you for availing us.