A monochromatic beam of light is incident at $$60^\circ$$ on one face of an equilateral prism of refractive index n and emerges from the opposite face making an angle $$\theta(n)$$ with the normal (see the figure). For $$n = \sqrt 3$$ the value of $$\theta$$ is $$60^\circ$$ and $$\frac{d \theta}{dn} = m$$. The value of m is