The function $f(x) =[x] \cos \bigg[ \large\frac{2x-1}{2}\bigg]$$\pi$ Where $[.]$ denotes the greatest integer function, is discontinuous at

Question

$\begin{array}{1 1} all\;x \\ all\;integer\;points \\ no\;x \\ x\;which\;is\;not\;an\;integer \end{array} $