<Verb>CayleyMetric(g,h):: Permutation, Permutation --> Int</Verb><P/>
<P/> Inputs two permutations <M>g,h</M> and optionally the degree <M>N</M>
of a symmetric group containing them. It returns the minimum number of
transpositions needed to express <M>g*h^{-1}</M>
as a product of transpositions.
