#include <iostream>
#include <iomanip>
using namespace std;

int main()
{
	double a;

	while (cin >> a) {

		double s = a;

		for (int i = 0; i < 4; i++) {
			a *= 2;
			s += a;
			a /= 3;
			s += a;
		}

		a *= 2;
		s += a;

		cout << setiosflags(ios::fixed | ios::showpoint) << setprecision(10) << s << endl;
	}

	return 0;
}
