Burning coal that contains sulfur releases sulfur trioxide gas into the atmosphere, where it combines with water to form sulfur and sulfuric acid, thereby producing acid rain. Assume sulfur in coal is in the form of pyrite (FeS2(s)), which reacts with molecular oxygen to produce Fe2O3(s) and SO3(g). Write the balanced equation for this reaction and report the sum of the stoichiometric coefficients, written as integers.