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.
Q: Passage: On 18 February 1921, the ARF led an anti-Soviet rebellion in Yerevan and seized power. The ARF controlled Yerevan and the surrounding regions for almost 42 days before being defeated by the numerically superior Red Army troops later in April 1921. The leaders of the rebellion then retreated into the Syunik region. On 26 April 1921, the 2nd Pan-Zangezurian congress, held in Tatev monastery, announced the independence of the self-governing regions of Daralakyaz , Zangezur, and Mountainous Artsakh, under the name of the Republic of Mountainous Armenia and later on 1 June 1921, it was renamed the Republic of Armenia.
Question: On what date did the ARF stop controlling Yerevan?
A:
date