Three Dimensional Geometry

The distance of a point $\mathbf{a}$ from the plane $\mathbf{r} \cdot \mathbf{m}=q$ is given by $\frac{|\mathbf{a} \cdot \mathbf{m}-9|}{|\mathbf{m}|}$. If the distance of the point $\hat{\mathbf{i}}+2 \hat{\mathbf{j}}+3 \hat{\mathbf{k}}$ from the plane $\mathbf{r} \cdot(2 \hat{\mathbf{i}}+6 \hat{\mathbf{j}}-9 \hat{\mathbf{k}})=-1$ is $p$ and the distance of the origin from this plane is $q$, then $p-q=$