BALKAN-SL 2019 C1
- Answer
100 couples are invited to a traditional Moldovan dance. The 200 people stand in a line, and then in a step, two of them (not necessarily adjacent) may swap positions. Find the least such that whatever the initial order, they can arrive at an ordering where everyone is dancing next to their partner in at most steps.
Dataset text NuminaMath olympiads. Quoted with source.
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N-1
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