Ooooh, kitties! They are so sweet. There are eight of them. Their fur comes in five colours. Five of them have black, four have white, two have orange, two have brown, and one has purple. (Paint or not, consider it a fur colour.) Each kitten has at least one fur colour.
Every kitten is special. That means that no two kittens have exactly the same fur colours.
How many of these mewing lovelies have exactly one fur colour?
Submit your answer to Gene Wirchenko <firstname.lastname@example.org>. Your answer should be in the form of a proof. That means to show how your answer must be correct. The deadline is Wednesday, December 3, 2014 at noon Pacific Time. I will post the answer shortly after.