The first two are Knights and the third is a Knave.
Basically, everyone says they're a Knight and no one ever says they're a Knave because Knights always tell the truth and Knaves always lie. The key is in the first half of the second persons response. He must be a Knight since, if he were a Knave, he would have lied about the first persons response saying "He says he is a Knave". Therefore, he must be telling the truth about the first, hence, both are Knights. That being said, the third person must then be a Knave since he was obviously lying.
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