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 _____.