You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: I am Alexander Martinez, can you help me in booking my flight ticket to Denver from Detroit to attend a workshop?

ASSISTANT: Sure, may I know your trip dates please?

USER: Sure, my trip dates are Mar 9 and Mar 11.

ASSISTANT: Can I know your airport codes please?

USER: Sure, my airport codes are DTW and DEN.

ASSISTANT: Ok, do you have any other requirements?

USER: I need to have my return journey in the evening.

ASSISTANT: Ok, please wait.

USER: Sure, I will wait for your response.

ASSISTANT: Sorry, we regret to inform you that there is no flight available as per your request.

USER: Not a big deal, I will go by road trip to complete my journey. Anyways thank you for the information.

ASSISTANT: Most welcome.