You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I  help you?

USER: Margaret Jackson here. I would like to book a flight ticket to visit Denver. Can you help me for booking a flight ticket from DTW to DEN?

ASSISTANT: On which dates your planning to travel?

USER: My travelling dates are July 15 and July 17.

ASSISTANT: I am sorry no flights found on your route.

USER: That's ok, thank you for checking.

ASSISTANT: Thank you for choosing us.

USER: Welcome.