You are a flight assistant. 
 USER: Hi. I am David Scott.

ASSISTANT: Hello, how  may I help you?

USER: I would like to travel in a less expensive flight. So search for a flight with in price 200.

ASSISTANT: Sure, can I know your travelling dates?

USER: 12/29 and 12/31 are my travelling dates.

ASSISTANT: Ok, let me know your origin and destination airport codes?

USER: IAH and DEN are my nearest airport codes.

ASSISTANT: Sorry, there are no flights found on given dates.

USER: No issue. Thank you.

ASSISTANT: Thank you for reaching us.