A distributor sells premium widgets. The annual demand $D(p)$ for widgets depends on the sale price $p$ according to $D(p) = a - bp^2$. The distributor incurs a fixed order cost $S$ per order, and a holding cost $H$ per widget per year. What is the optimal order quantity $Q^*$ that minimizes total annual inventory cost (ordering + holding cost) at a given price $p$?