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class Solution {
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 public:
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  bool isPrime(int n) {
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    for (int i = 2; i <= sqrt(n); i++)
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      if (n % i == 0) return false;
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    return true;
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  }
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  bool isThree(int n) {
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    return n != 1 && n != 2 && (int)sqrt(n) * sqrt(n) == n && isPrime(sqrt(n));
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  }
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};