Carlo Guasco (16 March 1813 – 13 December 1876) was a celebrated Italian operatic tenor who sang in Italian and other European opera houses from 1837 to 1853.
 Although he sang in many world premieres, he is most remembered today for having created the leading tenor roles in Verdi's "I Lombardi alla prima crociata", "Ernani", and "Attila".
Ernani is an operatic "dramma lirico" in four acts by Giuseppe Verdi to an Italian libretto by Francesco Maria Piave, based on the play "Hernani" by Victor Hugo.
Ernani do Nascimento Germano, better known as Ernani (São João da Barra, 16 July 1982) is a Brazilian footballer, who acts as a steering wheel and side.
 Currently playing for Juventude.
Corrado Zambelli (3 June 1897 - 1 September 1974) was an Italian classical bass who had an active international singing career in operas and concerts from the 1920s through the 1950s.
 He appears on several complete opera recordings, including "Otello" and "Carmen" for His Master's Voice; and "Ernani", "Il trovatore", "La favorite", and "La Gioconda" for Columbia Records.
Spanish tenor Plácido Domingo has officially sung 147 roles in Italian, French, German, English, Spanish and Russian.
 His main repertoire however is Italian ("Otello", Cavaradossi in "Tosca", "Don Carlo", Des Grieux in "Manon Lescaut", Dick Johnson in "La fanciulla del West", Radames in "Aida"), French ("Faust", "Werther", Don José in "Carmen", Samson in "Samson et Dalila"), and German ("Lohengrin", "Parsifal", and Siegmund in "Die Walküre").
 Domingo currently continues to add more operas to his repertoire.
 Since 2009, he has moved substantially into the baritone repertoire, especially focusing on Verdi baritone roles.
 In 2015, he made his most recent debuts as Macbeth at the Berliner Staatsoper, Don Carlo in "Ernani" at the Metropolitan Opera, and Gianni Schicchi at the Los Angeles Opera.
 Tim Page, a Pulitzer Prize-winner for music criticism, described Domingo in a 1996 "Washington Post" article as "the most versatile, intelligent and altogether accomplished operatic tenor now before the public."
Gaetano Mares (1793–1862) was an Italian conductor.
 He notably conducted the world premieres of Giuseppe Verdi's "Ernani" (1844), "Attila (opera)" (1846), "Rigoletto" (1851) and "La traviata" (1853) at La Fenice in Venice.
Sondra Radvanovsky (born April 11, 1969) is an American-Canadian soprano.
 Specializing in 19th-century Italian opera, Radvanovsky has been called one of the leading Verdi sopranos of her generation.
 Her signature roles include Elvira in "Ernani", Leonora in "Il trovatore", Elena in "I vespri siciliani", Élisabeth in "Don Carlos", and the title role in "Norma".
Stiffelio is an opera in three acts by Giuseppe Verdi, from an Italian libretto by Francesco Maria Piave.
 The origin of this was the novel “Le pasteur d’hommes”, by Émile Souvestre, which was published in 1838.
 This was adapted into the French play "Le pasteur, ou L'évangile et le foyer" by Émile Souvestre and Eugène Bourgeois.
 That was in turn translated into Italian by Gaetano Vestri as "Stifellius"; this formed the basis of Piave's libretto.
Aroldo (] ) is an opera in four acts by Giuseppe Verdi to an Italian libretto by Francesco Maria Piave, based on and adapted from their earlier 1850 collaboration, "Stiffelio".
 The first performance was given in the Teatro Nuovo Comunale in Rimini on 16 August 1857.
José Cura (born December 5, 1962 in Rosario, Argentina) is an Argentine operatic tenor, conductor, director, scenographer and photographer known for intense and original interpretations of opera characters, notably "Otello" in Verdi’s "Otello", "Samson" in Saint-Saëns’ "Samson et Dalila", "Canio" in Ruggero Leoncavallo's "Pagliacci", "Stiffelio" in Giuseppe Verdi's "Stiffelio" and many others.

Question: Which opera Ernani and Stiffelio.has more acts ?
Answer: Ernani