;Task:
Write a boolean function that tells whether a given integer is prime using [http://www.cut-the-knot.org/blue/Wilson.shtml Wilson's theorem]. 

By Wilson's theorem, a number '''p''' is prime if and only if '''p''' divides <code>(p - 1)! + 1</code>.

Remember that '''1''' and all non-positive integers are not prime.



;See also:
* [http://www.cut-the-knot.org/blue/Wilson.shtml Cut-the-knot: Wilson's theorem.]
* [[wp:Wilson's_theorem|Wikipedia: Wilson's theorem]]
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