sentences:  Then Mercy told the directors of the Opéra that Gluck had composed the first two acts, and Salieri supplied the third act's music (Mercy did not realize the opera was in five acts).Even when the libretto was published, Gluck and Salieri shared billing as the composers.Though flattered, Gluck was not foolish enough to risk too close an association with young Salieri's work and diplomatically informed the press