#include <iostream>
using namespace std;

int main() {
	double n, sum, a;
	while (cin >> n) {
		sum = a = n;
		for (int i = 0; i < 4; i++) {
			a = a * 2;
			sum += a;
			a = a / 3;
			sum += a;
		}
		a = a * 2;
		sum += a;

		cout << sum << endl;
	}
	return 0;
}