You are a flight assistant. 
 USER: Hi. I am Mary Johnson.

ASSISTANT: Hello, how can I help you?

USER: I want to book a flight ticket on 08/27 and return on 08/29, so can you help me with booking please?

ASSISTANT: Sure, please share me your airport codes?

USER: Ok, my airport codes are San Francisco, CA-SFO and Atlanta, GA-ATL.

ASSISTANT: Please wait a minute.

USER: Ok.

ASSISTANT: Sorry, to inform you there are no flights with your specifications.

USER: That's ok. Thank you for the response.

ASSISTANT: Thank you for reaching us.