Knights and Knaves: Olivia, Niaj, Peggy, and Heidi

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knights knaves

On an island, every inhabitant is either a knight, who always tells the truth, or a knave, who always lies. You meet Olivia, Niaj, Peggy, and Heidi. Olivia says: "Peggy is a knight and Heidi is a knave." Peggy says: "Niaj is a knave and Heidi is a knave." Heidi says: "Niaj is a knave and Olivia is a knight." The others say nothing. Who is a knight and who is a knave?

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Solution

Commit an attempt to unseal the proof. Write your answer — right or wrong, thinking it through is the point.

Once you've worked out who is who: how many of the 4 inhabitants are knaves? Answer with the number.

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