Solenoid magnetic field energy

$W = \frac{\mu\cdot \mu0\cdot n^{2}\cdot l^{2}\cdot V}{2}$

W - magnetic field energy
μ - relative magnetic permeability
μ0 - magnetic constant
n - number of turns in a winding per length unit
I - current intensity
V - bulk (volume)

Find It is known that:

Calculate 'W'