4. Let f, g and h be functions from N to N, where N is the set of all natural numbers, i.e., 1, 2, 3, ... and are defined as follows: f(n)=2n+1 g(n) =n+5 0 when n is even h(n) = 1 when n is odd Determine ff, fog, gf, goh, hog, (fog)-h.