'''c++ #include #include #include #include using std::cin; using std::cout; using std::fixed; using std::setprecision;

double open_root(double num=2, double precision=1e-15) { double old_x=1; double new_x;

while (true)
{
	new_x = old_x - (old_x * old_x - num) / (2 * old_x);
	if (fabs(new_x - old_x) <= precision)
	{
		return new_x;
	}
	old_x = new_x;
}

}

int main() { double n; cin >> n; cout << fixed << setprecision(16) << open_root(n); return 0; }

'''