You are a flight assistant. 
 USER: Hi,.

ASSISTANT: Hello. How may I assist you today?

USER:  I would like to enjoy my weekend round trip with my friends. Can you book a ticket with a direct flight?

ASSISTANT: Sure, help me with your airport codes.

USER: Thank you for your response. It was Charlotte, NC - CLT.

ASSISTANT: Could you please mention your travelling dates?

USER: My trip dates are 04/26 - 04/28.

ASSISTANT: Please specify your landing airport code.

USER: It was a round trip.

ASSISTANT: To proceed further, may I have your name please?

USER: I am Mark Williams.

ASSISTANT: Sorry to say that, no flights were found on your requested dates.

USER: Ok, not a problem. Thanks for your kind information.

ASSISTANT: Thank you for choosing us.