You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I help you today?

USER: Can you please book a flight ticket in economy class to attend a seminar?

ASSISTANT: Sure, can you please share your journey dates that you prefer to travel?

USER: Yes, my travelling dates are Oct 21 and 23.

ASSISTANT: May I know your airport codes?

USER: My airport codes are DCA and ATL.

ASSISTANT: Do you require any stopovers in your journey?

USER: Yes, I need a connecting flight.

ASSISTANT: Kindly share your airline preference.

USER: I want a ticket in normal cost, please check for a United airlines.

ASSISTANT: Would you let us know if you have any other preferences?

USER: Yes, I want to return in the afternoon.

ASSISTANT: Please share your name.

USER: My name is Dennis Lopez.

ASSISTANT: Ok, please wait a moment.

USER: Sure, take your time.

ASSISTANT: Sorry to say, no flights found with your requirement.

USER: That's ok, thank you for the response.

ASSISTANT: Thanks for reaching us.