A function $f$ is defined on $[ - 3,3 ]$ as
$$f ( x ) = \left\{ \begin{array} { c } \min \left\{ | x | , 2 - x ^ { 2 } \right\} , - 2 \leq x \leq 2 \\ { [ | x | ] , 2 < | x | \leq 3 } \end{array} \right.$$
where $[ x ]$ denotes the greatest integer $\leq x$. The number of points, where $f$ is not differentiable in $( - 3,3 )$ is $\underline{\hspace{1cm}}$.