void primes(int primes[], int n) {
    int nth_number = 0;
    for (int i=2; i<n; i++)
        for (int j=2; j*j<=i; j++)
        {
            if (i % j == 0)
                break;
            else if (j+1 > sqrt(i)) {
                cout << i << " ";
                primes[nth_number++] = i;
            }

        }
}