You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

USER: I am Christopher Smith. Can you help me to book a flight with 500 price limit?

ASSISTANT: Sure, help me with your trip dates.

USER: My travelling dates are 10/22 and 10/24.

ASSISTANT: May I know your airport codes?

USER: My airport codes are BOS and DTW.

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

USER: Ok, no issues.

ASSISTANT: Than you for opting us.

USER: Thank you for your information.