A Life for the Tsar is a  Russian libretto with four acts, Tosca an Italian libretto has how many acts?
A Life for the Tsar A Life for the Tsar (Russian: Жизнь за царя , "Zhizn' za tsarya"), as it is known in English, although in Soviet times its name was "Ivan Susanin" (Russian: Иван Сусанин ) is a "patriotic-heroic tragic opera" in four acts with an epilogue by Mikhail Glinka. The original Russian libretto, based on historical events, was written by Nestor Kukolnik, Egor Fyodorovich (von) Rozen, Vladimir Sollogub and Vasily Zhukovsky. It premiered on 27 November 1836 OS (9 December NS) at the Bolshoi Kamenny Theatre in St. Petersburg. The historical basis of the plot involves Ivan Susanin, a patriotic hero of the early 17th century who gave his life in the expulsion of the invading Polish army for the newly elected Tsar Mikhail, the first of the Romanov dynasty, elected in 1613.
Servilia (opera) Servilia (Russian: Сервилия , "Serviliya", the name of a main character), is an opera in five acts by Nikolai Rimsky-Korsakov. The work was completed in 1901, and was first performed in 1902 in St. Petersburg, Russia. The composer wrote the libretto, which is based on the drama by Lev Alexandrovich Mey. The story is set in Ancient Rome during Nero's reign.