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#include <iostream>
using namespace std;

bool isPrime(int n) {
    if (n <= 1)
    {
        return false;
    }

    if (n <= 3)
    {
        return true;
    }
    for (int i = 2; i * i <= n; i++) {
        if (n % i == 0)
        {
            return false;
        }

    }
    return true;
}

int main() {
    int i;

    cout << "Enter a positive integer: ";
    cin >>i;

    if (isPrime(i))
    {
        cout <<i<< " is a prime number." << endl;
    } else
    {
        cout <<i<< " is not a prime number." << endl;
    }

    return 0;
}