Task: Question Answering
Input (English): Passage: Manjakamiadana was built in two stages. The original palace, built between 1839 and 1840 on the orders of Ranavalona I, was built entirely in wood by Jean Laborde. In 1867, during the reign of Ranavalona II, a stone casing was erected around the original wooden structure.  The 30-metre (98 ft) long, 20-metre (66 ft) wide original wooden structure was 37 metres (121 ft) high, including the steeply pitched roof of wooden shingles, itself 15 metres (49 ft) in height. These measurements exclude the two superimposed balconies that extended 4.6 metres (15 ft) from the exterior walls and encircled the entire building, supported by 0.61-metre (2.0 ft) diameter wooden posts. The exterior of the entire building, including the roof, was painted white, with the exception of the balcony railings which were red. The exterior walls were composed of wooden planks tightly fitted together in a repeated chevron pattern reminiscent of traditional thatch walls, while the wood planks of the interior walls were hung vertically. The building could be entered by three doors: the main entrance in the northern wall, another in the southern wall and a third reserved for servants in the eastern wall.An open and spacious ground floor respected the same traditional layout exemplified in Besakana and other Merina homes, including the presence of hearth stones in their customary corner. Following traditional construction practices, the roof three stories above was supported by an enormous andry (central pillar) that was given the name Volamihitsy ("Genuine Silver"). According to popular legend, this was made of a single rosewood tree trunk transported from the eastern rain forests. Recent archaeological excavations of the site during reconstruction have since disproved this account as the pillar was found to be a composite of fitted rosewood pieces rather than a single solid post. According to custom, the north-eastern corner pillar was the first to be erected. Its length necessitated the use of a pulley designed by Jean Laborde, the principal architect, to haul the trunk into place. When an accident occurred during the operation, the queen designated a Malagasy carpenter to manufacture a crane to complete the task. Thousands of the queen's subjects were forced to labour on the building's construction in lieu of paying cash taxes pursuant to a tradition called fanampoana. One historic source claimed that 25,000 subjects participated in the raising of the building's corner posts alone. The harsh working conditions were said to have been the cause of many deaths, although precise figures are unknown. 
Question: Where were the three doors were the building could be entered?
Output (English): in the northern wall.