You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I guide you today?

USER: Myself Ashley Lopez. I would like to enjoy my weekend trip with my friends. Can you please book a ticket within the price of 200?

ASSISTANT: I am happy to help you with that.

USER: Thank you.

ASSISTANT: Can you please share your on what dates you are willing to travel?

USER: Sure, my travelling dates are 07/21 and 07/23.

ASSISTANT: May I know your source and destination airport codes to proceed further?

USER: Sure, my source airport code is DTW and my destination airport code is OAK.

ASSISTANT: Please wait for a minute.

USER: Ok, I will be waiting.

ASSISTANT: I am sorry to say that there is no flight found.

USER: That's ok, I will choose any other way to reach my destination on time. Thank you for your help.

ASSISTANT: Thank you for contacting us.