bool F(int[] a)
{
    int n = a.Length;
    Array.Sort(a);
    for (int i = 0; i < n - 1; i++)
        if (a[i] == a[i + 1])
            return false;
    return true;
}

int F(int n)
{
    int sum = 0;
    for (int i = 0; i < n; i++)
        for (int j = 0; j * j < n; j++)
        sum++;
    return sum;
}

int F(int n)
{
    while (n > 0)
    {
        int m = 1;
        while (m * 2 <= n)
            m *= 2;
        n -= m;
    }
    return n;
}