Let $f: \mathbb{R} \to \mathbb{R}$ be defined as

$f(x) = \begin{cases} \frac{a - b\cos 2x}{x^2}, & x < 0 \\ x^2 + cx + 2, & 0 \le x \le 1 \\ 2x + 1, & x > 1 \end{cases}$

If $f$ is continuous everywhere in $\mathbb{R}$ and $m$ is the number of points where $f$ is NOT differentiable, then $m + a + b + c$ equals: