The United States Postal Service charges more for boxes whose combined length and girth exceeds 108 in. The length of a package is the length $\ell$ of its longest side; the girth is the perimeter of the cross section, $2w + 2h$. What is the maximum volume of a package with a square cross section ( $w = h$ ) that does not exceed the 108 in. standard? Maximum volume $V =$ $\text{in}^3$