A Life for the Tsar is a  Russian libretto with four acts, Tosca an Italian libretto has how many acts?
Tosca Tosca (] ) is an opera in three acts by Giacomo Puccini to an Italian libretto by Luigi Illica and Giuseppe Giacosa. It premiered at the Teatro Costanzi in Rome on 14 January 1900. The work, based on Victorien Sardou's 1887 French-language dramatic play, "La Tosca", is a melodramatic piece set in Rome in June 1800, with the Kingdom of Naples's control of Rome threatened by Napoleon's invasion of Italy. It contains depictions of torture, murder and suicide, as well as some of Puccini's best-known lyrical arias.
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.