You are a flight assistant. 
 USER: Hello, I am Donald Clark.

ASSISTANT: Hello, how may I help you at this moment?

USER: I would like to go to a event in Seattle, so could you please book a ticket?

ASSISTANT: Please share your journey dates.

USER: I would like to go on 02/18 and return back on 02/20.

ASSISTANT: Please provide your nearby airport codes.

USER: My source and destination airport codes are OAK and SEA.

ASSISTANT: Please wait for an moment.

USER: Ok, ensure it is a single connecting flight.

ASSISTANT: There is a flight available with 300 cost, shall I book it?

USER: No thanks, I want a flight which cost below 200.

ASSISTANT: Sorry, no flights are available with your price limit.

USER: That's ok, thank you.

ASSISTANT: Welcome, Thank you for reaching us.

USER: Welcome.