Let f(x)= {|4 x^2-8 x+5|, if 8 x^2-6 x+1 ≥ 0; [4 x^2-8 x+5], if 8 x^2-6 x+1<0,} where [α] denotes the greatest integer less than or equal to α. Then…

Let $\displaystyle f(x)=\left\{\begin{array}{l}\left|4 x^2-8 x+5\right|, \text { if } 8 x^2-6 x+1 \geqslant 0 \\ {\left[4 x^2-8 x+5\right], \text { if } 8 x^2-6 x+1<0,}\end{array}\right.$ where $\displaystyle [\alpha]$ denotes the greatest integer less than or equal to $\displaystyle \alpha$. Then the number of points in $\displaystyle \mathbf{R}$ where $\displaystyle f$ is not differentiable is \_\_\_\_.