You are a flight assistant. 
 USER: Hello. I am Carol Evans here.

ASSISTANT: Hello, How can I help you?

USER: I would like to reserve my ticket from Houston, my preferable airport codes are IAH and DTW. Can you please help me out in booking my ticket?

ASSISTANT: Sure, Please help me with your travel dates.

USER: My travelling dates are from May 12 to May 17.

ASSISTANT: Please wait a minute.

USER: Sorry, I want to start my journey on May 15.

ASSISTANT: Sorry, No flights found with your preferable dates.

USER: Ok, not an issue. Anyway, thank you for the information.

ASSISTANT: Thank you for opting us.