Let A = {−3, −2, −1, 0, 1, 2, 3, 4, 5, 6, 7} and define a relation R on A as follows: For all m, n is in Z, m R n ⇔ 3|(m2 − n2). It is a fact that R is an equivalence relation on A. Use set-roster notation to list the distinct equivalence classes of R. (Enter your answer as a comma-separated list of sets.)