Teacher:This task involves annotating the answer type to a given question that involve some kind of complex reasoning (including numerical reasoning). Note that the questions require looking at more than one part of the passage to answer. There are 3 possible answer types (i) spans, (ii) numbers and (iii) dates. If the answer can be found in the passage, label it as "span". If the answer is a number, label as "number". Similarly, label "date" if you think the answer to the given question is a date.
Teacher: Now, understand the problem? Solve this instance: Passage: The intervention of Denmark, Sweden and Poland-Lithuania into Livonia began a period of struggle for control of the Baltic, known contemporaneously as the dominium maris baltici. While the initial war years were characterised by intensive fighting, a period of low-intensity warfare began in 1562 and lasted until 1570 when fighting once more intensified. Denmark, Sweden and to some extent Poland-Lithuania were occupied with the Nordic Seven Years' War taking place in the Western Baltic, but Livonia remained strategically important. In 1562, Denmark and Russia concluded the Treaty of Mozhaysk, respecting each other's claims in Livonia and maintaining amicable relations. In 1564, Sweden and Russia concluded a seven-years truce. Both Ivan IV and Eric XIV showed signs of mental disorder, with Ivan IV turning against part of the Tsardom's nobility and people with the oprichina that began in 1565, leaving Russia in a state of political chaos and civil war.
Question: How many years did the period of low-intensity warfare last?
Student:
number