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

int main() {
	double d[10];
	double a;
	while (cin >> a) {
		d[0] = a;
		d[1] = d[0] * 2;
		for (int i = 2; i < 10; i + 2) {
			d[i] = d[i - 1] / 3;
			d[i + 1] = d[i] * 2;
		}
		int ca=0;
		for (int i = 0; i < 10; i++) {
			ca += d[i];
		}
		cout << fixed << setprecision(9) << ca << endl;
	}
	return 0;
}