#include <iostream>
#include <stdio.h>
using namespace std;

int main()
{
	double a, n[10] = {};

	while (cin >> a)
	{
		n[0] = a;
		double sum = n[0];
		for (int i = 1; i < 10; i++)
		{
			if (i % 2 == 1) n[i] = n[i - 1] * 2;
			else  n[i] = n[i - 1] / 3.0; 
			sum += n[i];
	//		cout << n[i] << " ";
		}
		//cout << endl;
		printf("%.6f\n", sum);
	}
	return 0;
}
