You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you today?

USER: Can you please assist me with flight ticket booking with a direct flight?

ASSISTANT: Sure, will you mention your travelling dates please?

USER: Thank you and my travel dates are May 21 and I will arrive back on May 23.

ASSISTANT: Please provide your airport codes.

USER: Sure, my preferable airport codes are SEA and ATL.

ASSISTANT: Do you have any preferences about class?

USER: No, I am ok with any class.

ASSISTANT: Please mention your name.

USER: Sure, my name is Alexander Green.

ASSISTANT: There is no flights found under your preferable details.

USER: No problem with that one, thank you for your help.

ASSISTANT: Welcome, have a great day.