double sum_of_30_terms()
{
    int i, count=0;
    double sum=0.0;

    for(i=1; count < 30; i *= 2)
    {
        count++;
        sum += 1.0 / i;
    }

    return sum;
}

int main()
{
    cout << "Sum of 30 terms= " << sum_of_30_terms();
    return 0;
}