During the 18th and 19th century, Hungarian Hussars rose to international fame and served as a model for light cavalry in many European countries. In 1848-49 HDF achieved incredible successes against better-trained and equipped Austrian forces, despite the obvious advantage in numbers on the Austrian side. The 1848-49 Winter Campaign of Józef Bem and the Spring Campaign of Artúr Görgey are to this day taught at prestigious military schools around the globe, including at West Point Academy in the United States. In 1872, the Ludovica Military Academy officially began training cadets. By 1873 HDF already had over 2,800 officers and 158,000 men organized into eighty-six battalions and fifty-eight squadrons. During World War I out of the eight million men mobilized by Austro Hungarian Empire, over one million died. During the 1930s and early 1940s, Hungary was preoccupied with the regaining the vast territories and huge amount of population lost in the Trianon peace treaty at Versailles in 1920. Conscription was introduced on a national basis in 1939.  The peacetime strength of the Royal Hungarian Army grew to 80,000 men organized into seven corps commands. During World War II the Hungarian Second Army was near to total devastation on banks of the Don River (Russia) in December 1942 in Battle for Stalingrad. During the Socialist and the Warsaw Pact era (1947-1989), the entire 200,000 strong Southern Group of Forces was garrisoned in Hungary, complete with artillery, tank regiments, air force and missile troops with nuclear weapons.
Question: How many years after the signing if the Trianon peace treaty did Hungary introduce conscription?
Answer: 19