Which opera  Pelléas et Mélisande and Die schweigsame Frau has fewer acts ?
Pelléas et Mélisande (opera) Pelléas et Mélisande ("Pelléas and Mélisande") is an opera in five acts with music by Claude Debussy. The French libretto was adapted from Maurice Maeterlinck's Symbolist play "Pelléas et Mélisande". It premiered at the Opéra-Comique in Paris on 30 April 1902 with Jean Périer as Pelléas and Mary Garden as Mélisande in a performance conducted by André Messager, who was instrumental in getting the Opéra-Comique to stage the work. The only opera Debussy ever completed, it is considered a landmark in 20th-century music.
Lohengrin (Sciarrino) Lohengrin "(Azione invisibile per solista, strumenti e voci)" is an operatic monodrama by the Italian composer Salvatore Sciarrino. Premiered in 1982 in Milan the work was later revised by Sciarrino and the new version was premiered in on 9 September 1984 in Catanzaro. The opera, which is less than an hour long, is loosely based on the plot of Wagner’s opera of the same name.