$\lambda = m^{p}v^{q}h^{r}$ $\left\lbrack M^{0}LT^{0} \right\rbrack = \left\lbrack M^{p} \right\rbrack\left\lbrack LT^{- 1} \right\rbrack^{q}\left\lbrack ML^{2}T^{- 2} \right\rbrack^{r}$ $\left\lbrack M^{0}LT^{0} \right\rbrack = \lbrack M^{p + r}L^{q + 2r}T^{- q - r}\rbrack$ $\therefore\ \ \ p + r = 0,q + 2r = 1, - q - r = 0$ After solving we get $p = - 1,q = - 1,r = 1$