A long cylindrical wire of radius \(R\) carries a non-uniform current density parallel to its central axis given by \(J(r) = C r^2\), where \(r\) is the radial distance from the central axis and \(C\) is a constant. Let \(J_{\text{max}}\) be the maximum current density at the outer surface of the wire, and let \(A = \pi R^2\) be the cross-sectional area of the wire. What is the total current \(I\) flowing through the wire?