4. Let n > 3. Consider the digraph G(V, E) where V = [n] and %3D E = {(i, 2i) i < n/2} U{(i, 2i + 1)|i < (n 1)/2}. %3D - (a) Prove that G is a directed tree. (b) Let m e [n]. What is the out-degree and in-degree of the vertex m of G. Prove your answer.