question: Efrem Flaks was the original performer of songs composed by which other Soviet film composer?
answer: Matvei Isaakovich Blanter
context: Title: Late for a Date
  Passage: Late for a Date (Russian: Девушка спешит на свидание , "Devushka speshit na svidanie " ; literally "Girl in a hurry for a date") is a Soviet comedy film directed by Mikhail Verner.  A new print was issued in 1987, completely redubbed apart from the songs performed by Efrem Flaks.
  Title: Vladimir Nechaev
  Passage: Vladimir Alexandrovich Nechaev (Russian: Влади́мир Алекса́ндрович Неча́ев ; 28 July 1908 — 11 April 1969) was a Soviet singer, a lyric tenor.  A holder of the title of Meritorious Artist of the RSFSR since 1959.  A soloist of the USSR All-State Radio since 1942.  The original performer of a number of songs by such composers as Boris Mokrousov, Vasily Solovyov-Sedoi, Matvey Blanter.  In 1944 he formed a duet with Vladimir Bunchikov, a highly acclaimed collaboration that continued for 25 years, until Nechaev's death in 1969.
  Title: Vladimir Troshin
  Passage: Vladimir Konstantinovich Troshin (Russian: Влади́мир Константи́нович Тр́ошин ; 15 May 1926 — 25 February 2008) was a Soviet and Russian film and theater actor, singer.  In 1951, at the age of 25, for his portrayal of a rural inventor in the play "Second Love" at the Moscow Art Theater he was awarded the Stalin Prize (2nd degree).  Troshin was the original performer of the song "Moscow Nights" that in 1957 brought him fame all over the Soviet Union.  He was made a People's Artist of the RSFSR in 1985.
  Title: The Cranes Are Flying
  Passage: The Cranes Are Flying (Russian: Летят журавли , translit.  "Letyat zhuravli") is a 1957 Soviet film about World War II.  It depicts the cruelty of war and the damage suffered to the Soviet psyche as a result of World War II (known in the Soviet Union as the Great Patriotic War).  It was directed at Mosfilm by the Georgian-born Soviet director Mikhail Kalatozov in 1957 and stars Aleksey Batalov and Tatiana Samoilova.  It won the "Palme d'Or" at the 1958 Cannes Film Festival, the only Soviet film to win that award, although "The Turning Point" (1946) was one of eleven films awarded that year's Grand Prix, the predecessor of the "Palme d'Or".
  Title: Johanna Jachmann-Wagner
  Passage: Johanna Jachmann-Wagner or Johanna Wagner (13 October 1828 – 16 October 1894) was a mezzo-soprano singer, tragédienne in theatrical drama, and teacher of singing and theatrical performance who won great distinction in Europe during the third quarter of the 19th century.  She was a niece of the composer Richard Wagner and was the original performer, and in some respects the inspiration, of the character of Elisabeth in "Tannhäuser".  She was also the original intended performer of Brünnhilde in "Der Ring des Nibelungen", but in the event assumed other roles.
  Title: Matvey Blanter
  Passage: Matvei Isaakovich Blanter (Russian: Матве́й Исаа́кович Бла́нтер ) (10 February [O.S. 28 January] 1903 27 September 1990) was one of the most prominent composers of popular songs and film music in the Soviet Union.  Among many other works, he wrote the internationally famous "Katyusha" (1938), performed to this day internationally.  He was active as a composer until 1975, producing more than two thousand songs.
  Title: Isaak Dunayevsky
  Passage: Isaak Osipovich Dunayevsky (Russian: "Исаак Осипович Дунаевский" ; also transliterated as Dunaevski or Dunaevsky; 30 January [O.S. 18 January] 1900 25 July 1955) was a Soviet film composer and conductor of the 1930s and 1940s, who achieved huge success in music for operetta and film comedies, frequently working with the film director Grigori Aleksandrov.  He is considered one of the greatest Soviet composers of all time.  Many of his songs are very well known and held in high regard in Russia and the former Soviet Union.
  Title: Yuri Bogatikov
  Passage: Yuri losifovich Bogatikov (Russian: Ю́рий Ио́сифович Бога́тиков ; 29 February 1932, Rykovo, Donetsk oblast, Ukrainian SSR, USSR — 8 December 2002, Simferopol, Autonomous Republic of Crimea, Ukraine) was a Soviet and Ukrainian singer (baritone).  In 1985 he was honoured with the title of People's Artist of the USSR.  His repertoire consisted of over 400 songs.  He was the original performer of such songs as "I Haven't Been in Donbass for a Long Time" ("Давно не бывал я в Донбассе" by Bogoslovsky), "Let's Talk" ("Давай, поговорим" by Hanok), "Don't Let Your Heart Cool Down, My Son" ("Не остуди своё сердце, сынок" by Migulya), "Remembering the Regimental Band" ("Воспоминание о полковом оркестре" by Gulyaev).
  Title: Efrem Flaks
  Passage: Efrem Borisovich Flaks (Russian: Ефре́м Бори́сович Флакс ; 15 January [O.S. 2 January] 1909 — 17 December 1982) was a Soviet singer (bass).  A holder of the title of Meritorious Artist of the RSFSR since 1960.  He graduated from the Leningrad Conservatory (vocal class) in 1936, from 1939 to 1942 and from 1950 to 1970 worked as a soloist at the Leningrad Philharmonia, from 1943 to 1950 at the Leningrad Radio.  He was the original performer of numerous songs by composers Vasily Solovyov-Sedoi, Matvey Blanter, Boris Mokrousov, etc.
citations: Efrem Flaks Matvey Blanter