Which one vanishes

[Fu-Kwun Hwang]

Which one vanishes? 哪一個消失了

Count the number of Leprechuan before you click the buton,
 count it again after you click the button.
And find out which one vanishes?

You can print out the above image, cut the upper half into two parts, and switch thos two parts.

   original ideal from "The Vanishing Leprechuan"