The Black Sea Fleet  is the fleet of the Russian Navy in the Black Sea, the Sea of Azov and the Mediterranean Sea. The fleet is considered to have been founded by Prince Potemkin on May 13, 1783. In 1918, the fleet was inherited by the Russian SFSR then the Soviet Union in 1922, where it became part of the Soviet Navy. Following the collapse of the Soviet Union in 1991, the Black Sea Fleet and most of its vessels were inherited by the Russian Federation. The Black Sea Fleet's official primary headquarters and facilities are located in the city of Sevastopol, which is de jure part of Ukraine but de facto part of Russia . The remainder of the fleet's facilities are based in various locations on the Black Sea and the Sea of Azov, including Krasnodar Krai, Rostov Oblast and Crimea. The current commander is Admiral Aleksandr Viktorovich Vitko, who has held the position since April 2013.
Question: How many years after the fleet was inherited by the Russian SFSR was it then inherited by the Soviet Union?
Answer: 4