You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, do you need any help from us?

USER: Please help me to book a flight ticket from SEA to ATL?

ASSISTANT: Sure, could you please share your departure and arrival day?

USER: My travelling dates are July 30 to Aug 1.

ASSISTANT: Ok, could I have your name please?

USER: David Lopez here.

ASSISTANT: Ok, do you have any other specifications?

USER: I would like to prefer economy class.

ASSISTANT: Sorry, there is no flight on your requested travelling dates.

USER: No problem, thank you.

ASSISTANT: You are welcome, have a great day.