Electrostatics

Four point charges, each of +q, are rigidly fixed at the four corners of a square planar soap film of side a. The surface tension of the soap film is \(\gamma\). The system of charges and planar film are in equilibrium, and \(a = k{\left[ {{{{q^2}} \over \gamma }} \right]^{1/N}}\), where k is a constant. Then N is __________.