Task: Question Answering
Input (English): Passage: The idea of building a memorial to honor soldiers killed in action during the Latvian War of Independence first emerged in the early 1920s. On July 27, 1922, the Prime Minister of Latvia, Zigfrīds Anna Meierovics, ordered rules to be drawn up for a contest for designs of a "memorial column". The winner of this contest was a scheme proposing a column 27 meters (89 ft) tall with reliefs of the official symbols of Latvia and bas-reliefs of Krišjānis Barons and Atis Kronvalds. It was later rejected after a protest from 57 artists. In October 1923, a new contest was announced, using for the first time the term "Freedom Monument". The contest ended with two winners, and a new closed contest was announced in March 1925, but, due to disagreement within the jury, there was no result.Finally in October 1929, the last contest was announced. The winner was the design "Shine like a star!" (Latvian: "Mirdzi kā zvaigzne!") by sculptor Kārlis Zāle, who had had success in the previous contests as well. After minor corrections made by the author and supervising architect Ernests Štālbergs, construction began on November 18, 1931. Financed by private donations, the monument was erected by the entrance to the old town, in the same place where the previous central monument of Riga, a bronze equestrian statue of the Russian Emperor Peter the Great had stood from 1910 until the outbreak of World War I. It was calculated in 1935, the year when the monument was unveiled, that in four years of construction 308,000 man-hours were required to work the stone materials alone: 130 years would have been required if one person were to carry out the work using the most advanced equipment of the time. The total weight of materials used was about 2,500 tons: such a quantity of materials would have required about 200 freight cars if transported by railway. 
Question: How many man-hours were required to build the memorial that was the result of a contest ordered by the Prime Minister of Latvia?
Output (English): 308,000.