The "Farewell Symphony", No. 45 in F minor, exemplifies Haydn's integration of the differing demands of the new style, with surprising sharp turns and a long slow adagio to end the work. In 1772, Haydn completed his Opus 20 set of six string quartets, in which he deployed the polyphonic techniques he had gathered from the previous Baroque era to provide structural coherence capable of holding together his melodic ideas. For some, this marks the beginning of the "mature" Classical style, in which the period of reaction against late Baroque complexity yielded to a period of integration Baroque and Classical elements.