Let f: ℝ → ℝ be a function defined as f(x) = {
3(1 - |x|^2) if |x| ≤ 2,
0 if |x| ≥ 2
}

Let g: ℝ → ℝ be given by g(x) = f(x + 2) - f(x - 2). If n and m denote the number of points in ℝ where g is not continuous and not differentiable, respectively, then n + m is equal to _______.