ABC is a plane lamina of the shape of an equilateral triangle. $\mathrm{D}, \mathrm{E}$ are mid points of $\mathrm{AB}, \mathrm{AC}$ and G is the centroid of the lamina. Moment of inertia of the lamina about an axis passing through G and perpendicular to the plane ABC is IO . If part ADE is removed, the moment of inertia of the remaining part about the same axis is $\frac{\mathrm{NI}_0}{16}$ where N is an integer. Value of $N$ is $\_\_\_\_$ .