If p and q are respectively the order and degree of the differential equation d/(d x)(dy/(d x))^3=0, then ( p - q ) is

If $\displaystyle \mathrm{p}$ and $\displaystyle \mathrm{q}$ are respectively the order and degree of the differential equation $\displaystyle \frac{\mathrm{d}}{\mathrm{d} x}\left(\frac{\mathrm{dy}}{\mathrm{d} x}\right)^{3}=0$, then $\displaystyle (\mathrm{p}-\mathrm{q})$ is