Let m be the minimum possible value of, log3(3y1 + 3y2 + 3y3) where y1, y2, y3 are real numbers for which y1 + y2 + y3 = 9. Let M be the maximum possible value of (log3x1 + log3x2 + log3x3), where x1, x2, x3 are positive real numbers for which x1 + x2 + x3 = 9. Then the value of log2(m3) + log3(M2) is ______.