Question: Leoš Janáček and Sergei Prokofiev are both what?

Context paragraphs:
Destiny (Janáček): Destiny (also known as "Fate", Czech: "Osud" ) is an opera in three acts by Leoš Janáček to a Czech libretto by the composer and Fedora Bartošová.  Janáček began the work in 1903 and completed it in 1907.  The inspiration for the opera came from a visit by Janáček in the summer of 1903, after the death of his daughter Olga, to the spa at Luhačovice.  There, Janáček met Kamila Urválková, who had been the subject of an opera by Ludvík Čelanský, "Kamila", where she felt that Čelanský had falsely depicted her personality.  After learning that Janáček was a composer, Urválková persuaded Janáček to write another opera to counteract Čelanský's portrait of her.

Semyon Kotko: Semyon Kotko (Russian: Семён Котко ), Op. 81, is an opera in five acts by Sergei Prokofiev to a libretto by Sergei Prokofiev and Valentin Katayev based on Katayev's 1937 novel "I, Son of Working People" (Russian: Я, сын трудового народа… ).  It was premiered on 23 June 1940 at the Stanislavsky Opera Theatre in Moscow.

Leoš Janáček: Leoš Janáček (] , baptised Leo Eugen Janáček; 3 July 1854 – 12 August 1928) was a Czech composer, musical theorist, folklorist, publicist and teacher.  He was inspired by Moravian and other Slavic folk music to create an original, modern musical style.

Sinfonietta (Janáček): The Sinfonietta (subtitled “Military Sinfonietta” or “Sokol Festival”) is a very expressive and festive, late work for large orchestra (of which 25 are brass players) by the Czech composer Leoš Janáček.  It is dedicated “To the Czechoslovak Army” and Janáček said it was intended to express “contemporary free man, his spiritual beauty and joy, his strength, courage and determination to fight for victory.”  It started by Janáček listening to a brass band, becoming inspired to write some fanfares of his own.  When the organisers of the Sokol Gymnastic Festival approached him for a commission, he developed the material into the "Sinfonietta".  He later dropped the word "military".  The first performance was in Prague on 26 June 1926 under Václav Talich.  Typical performance duration is 20–25 minutes.

Sergei Prokofiev: Sergei Sergeyevich Prokofiev ( ; Russian: Сергей Сергеевич Прокофьев , "Sergej Sergejevič Prokofjev" ; 27 April 1891 – 5 March 1953) was a Soviet composer, pianist and conductor.  As the creator of acknowledged masterpieces across numerous musical genres, he is regarded as one of the major composers of the 20th century.  His works include such widely heard works as the March from "The Love for Three Oranges," the suite "Lieutenant Kijé", the ballet "Romeo and Juliet" – from which "Dance of the Knights" is taken – and "Peter and the Wolf."  Of the established forms and genres in which he worked, he created – excluding juvenilia – seven completed operas, seven symphonies, eight ballets, five piano concertos, two violin concertos, a cello concerto, a Symphony-Concerto for cello and orchestra, and nine completed piano sonatas.

Leoš Firkušný: Leoš Firkušný was a Czech musicologist.  He was born on July 16, 1905 in Napajedla (today's Czech Republic).  He was an older brother of the famous pianist Rudolf Firkušný.  He was an expert on Leoš Janáček and did much to bring his music to the listeners abroad.  He was one of the founders of the music festival Prague Spring.  He died on July 9, 1950 in Buenos Aires, Argentina.

Leoš Janáček International Competition in Brno: The Leoš Janáček International Competition in Brno (hereinafter referred to as MSLJ) (Czech: Mezinárodní soutěž Leoše Janáčka v Brně ) is a music competition held annually by the Faculty of Music of the Janáček Academy of Music and Performing Arts Brno.  The MSLJ was named after the famous composer Leoš Janáček.

Janáček (crater): Janáček is a crater on Mercury.  It has a diameter of 47 kilometers.  Its name was adopted by the International Astronomical Union in 1985.  Janáček is named for the Czech composer Leoš Janáček, who lived from 1854 to 1928.

Káťa Kabanová: Káťa Kabanová (also known in various spellings including "Katia", "Katja", "Katya", and "Kabanowa") is an opera in three acts, with music by Leoš Janáček to a libretto by , based on "The Storm", a play by Alexander Ostrovsky.  The opera was also largely inspired by Janáček's love for Kamila Stösslová.  This is often considered his first "mature" opera, despite the fact that he was 67 when it was premiered.  "Káťa Kabanová" is a clear response to Janáček's feelings for Kamila, and the work is dedicated to her.  The first performance was at the National Theatre (Národní divadlo v Brně ) in Brno on 23 November 1921.

Visions fugitives: Visions fugitives, Op. 22, are a series of short piano pieces composed by Russian composer Sergei Prokofiev (1891–1953) between 1915 and 1917.  They were premiered by Prokofiev on April 15, 1918 in Petrograd, Soviet Union.  They were written individually, many for specific friends of Prokofiev's, and he originally referred to them as his "doggies" because of their "bite".  In August 1917, Prokofiev played them for Russian poet Konstantin Balmont, and others, at the home of a mutual friend.  Balmont was inspired to compose a sonnet on the spot, called "a magnificent improvisation" by Prokofiev who named the pieces ""Mimolyotnosti"" from these lines in Balmont's poem: ""In every fleeting vision I see worlds, Filled with the fickle play of rainbows"".  A French-speaking friend at the house, Kira Nikolayevna, immediately provided a French translation for the pieces: "Visions Fugitives".  Prokofiev often performed only a couple of them at a time as encores at the end of his performances.

Supporting paragraphs: Leoš Janáček Sergei Prokofiev
Answer: composer