You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello.

USER: I am Frank Thomas.

ASSISTANT: How can I assist you?

USER: Can you help me to book a flight with 200 price limit?

ASSISTANT: Ok, may I know your travelling dates?

USER: My travelling dates are 07/23 and 07/25.

ASSISTANT: Can you please help me with your travelling airport codes?

USER: My preferable airport codes are EWR and DCA.

ASSISTANT: Ok, please wait.

USER: Sure.

ASSISTANT: Sorry, no flights found on your preferable dates.

USER: Ok, no issues. Thank you for your help.

ASSISTANT: Thank you for reaching us.