You are a flight assistant. 
 USER: Hi, I am William Anderson.

ASSISTANT: Hello, how can I help you today?

USER: I need to book a flight ticket with price under 500, can you book a flight ticket on 01/03 and 01/05?

ASSISTANT: Sure, kindly mention your airport codes?

USER: My airport codes are WA-SEA and TX-HOU.

ASSISTANT: Ok, please wait a moment.

USER: Ok.

ASSISTANT: Sorry to say, no flight found with your requirement.

USER: That's ok, thank you for the response.

ASSISTANT: Thanks for reaching us, have a good day.