4. Prove the given statement by indicated method. (48 points, 16 each) (1). By direct proof "For any integer n, there exist two integers a and b of opposite parity such that an + b is an odd integer." (2). By Contrapositive "If p is a prime greater than or equal to 5, then either 3 | (p + 2) or 3 | (p - 2)"