Definition: In this task, a passage will be given and the goal is to identify an event from the passage. An event is defined as a single word representing something that happened, is happening, or may happen. An event can be factual or hypothetical, positive or negative, certain or uncertain. While most events are based on verbs, an event can also be based on a noun (ex. storm, snow, rainfall) or a copula verb (is, was, been, etc.). The event must not be a pronoun or an adjective. For noun events with multiple words, use the last word in the phrase as event.
Input: Passage: But Lankov argued that they should be seen as the "advance guard" of the inevitable eventual reunification of the peninsula after the North's system collapsed. "The experience of living with them will be very helpful when living with not 10,000 but 24 million."

collapsed