Does Werther or War and Peace have more acts?
War and Peace (opera) War and Peace (Op. 91) (Russian: Война и мир , "Voyna i mir") is an opera in two parts (an Epigraph and 13 scenes), sometimes arranged as five acts, by Sergei Prokofiev to a Russian libretto by the composer and Mira Mendelson, based on the novel "War and Peace" by Leo Tolstoy. Although Tolstoy's work is classified as a novel, the 1812 invasion of Russia by the French was based on real-life events, and some real-life people appear as characters in both the novel and the opera, e.g. Prince Mikhail Kutuzov and Napoleon Bonaparte.
I puritani I puritani ("The Puritans") is an opera in by Vincenzo Bellini. It was originally written in two acts and later changed to three acts on the advice of Gioachino Rossini, with whom the young composer had become friends. The music was set to a libretto by Count Carlo Pepoli, an Italian émigré poet whom Bellini had met at a salon run by the exile Princess Belgiojoso, which became a meeting place for many Italian revolutionaries.