Continuity and Differentiability of Function

Let f:R→R be a function defined asf(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 whereg is not continuous and not differentiable,respectively, then n+m is equal to _______.