Detailed Instructions: 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.
Problem:Passage: Svitrigaila was losing his influence in the Slavic principalities and could no longer resist Poland and Sigismund. On 4 September 1437 he attempted to reconcile with Poland: he would rule the lands that still backed him , and after his death these territories would pass to the King of Poland. However, under strong protest from Sigismund, the Polish Senate declined to ratify the treaty . In 1438 Svitrigaila withdrew to Moldavia. The reign of Sigismund Kestutaitis was brief he was assassinated in 1440. Svitrigaila returned from exile in 1442 and ruled Lutsk until his death a decade later. Jogaila's son Casimir IV Jagiellon, born in 1426, received approval as a hereditary hospodar from Lithuania's ruling families in 1440. This event is seen by the historians Jerzy Lukowski and Hubert Zawadzki as marking the end of the succession dispute.
Question: What year did Svitrigalia die?
Solution:
date