A square shaped hole of side $I=\frac{a}{2}$ is carved out at a distance $d=\frac{a}{2}$ from the centre ' $O$ ' of a uniform circular disk of radius $a$. If the distance of the centre of mass of the remaining portion from $O$ is $-\frac{a}{x}$, value of $X$ (to the nearest integer) is $\_\_\_\_$ .