Teacher:This task involves creating answers to complex questions, from a given passage. Answering these questions, typically involve understanding multiple sentences. Make sure that your answer has the same type as the "answer type" mentioned in input. The provided "answer type" can be of any of the following types: "span", "date", "number". A "span" answer is a continuous phrase taken directly from the passage or question. You can directly copy-paste the text from the passage or the question for span type answers. If you find multiple spans, please add them all as a comma separated list. Please restrict each span to five words. A "number" type answer can include a digit specifying an actual value. For "date" type answers, use DD MM YYYY format e.g. 11 Jan 1992. If full date is not available in the passage you can write partial date such as 1992 or Jan 1992. If you find multiple spans, please add them all as a comma separated list. Please restrict each span to five words.
Teacher: Now, understand the problem? Solve this instance: Passage: In 1227 the Livonian Brothers of the Sword conquered all Danish territories in Northern Estonia. After the Battle of Saule the surviving members of the Brothers of the Sword merged into the Teutonic Order of Prussia in 1237 and became known as Livonian Order. On 7 June 1238, by the Treaty of Stensby, the Teutonic knights returned the Duchy of Estonia to Valdemar II, until in 1346, after St. George's Night Uprising, the lands were sold back to the order and became part of the Ordenstaat. After the conquest, all of the remaining local population were ostensibly Christianized. In 1535, the first extant native language book was printed, a Lutheran catechism. The conquerors upheld military control through their network of castles throughout Estonia and Latvia. The land was divided into six feudal principalities by Papal Legate William of Modena: Archbishopric of Riga, Bishopric of Courland, Bishopric of Dorpat, Bishopric of Osel-Wiek, the lands ruled by the Livonian Brothers of the Sword and Dominum directum of King of Denmark, the Duchy of Estonia.
Question: How many years after the Teutonic knights returned the Duchy of Estonia to Valdemar II did the lands get sold back to the order and became part of the Ordenstaat?
Answer type: Number
Student:
108.