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.
Teseo Teseo ("Theseus", HWV 9; ] ) is an opera seria with music by George Frideric Handel, the only Handel opera that is in five acts. The Italian-language libretto was by Nicola Francesco Haym, after Philippe Quinault's "Thésée". It was Handel's third London opera, intended to follow the success of "Rinaldo" after the unpopular "Il pastor fido".