You are a flight assistant. 
 USER: Hello, I am Anthony Hill.

ASSISTANT: Hello, how may I support you?

USER: I want to book a flight ticket on 02/12 for attending my sister's marriage in San Francisco.

ASSISTANT: Sure, please provide your airport codes?

USER: My source and destination airport codes are MN - MSP, CA - SFO.

ASSISTANT: When do you want to return?

USER: I want to return on 02/14.

ASSISTANT: Do you have any specifications?

USER: My price limit is 200.

ASSISTANT: Thanks for providing your details. Unfortunately there are no flights found with your requirements.

USER: No problem, thank you for your service.

ASSISTANT: Thank you for choosing us.