The following algorithm is supposed to compute n2n for any given natural number n{0,1,2,} Algorithm power2n(n) // Calculate n2n //Input: n{0,1,2} //Output: n2n counter n product 1 while (counter >0 ) product product* nn counter counter 1 return product Show all loop invariants (self-contained proposition that can be used to prove the correctness of the algorithm)