#include <bits/stdc++.h>

using namespace std;
 
int main()
{
    double n, s[10];
     
    while (cin >> n) {
        double ans = 0.0;
        s[0] = n;         
        for (int i = 1; i < 10; i++) {
            if ((i+1) % 2 == 0) {
                s[i] = 2.0 * s[i-1];
            } else {
                s[i] = s[i-1] / 3.0;
            }
        }
        for (int i = 0; i < 10; i++) {
            ans += s[i];
        }
        printf("%.8f\n" ,ans);
    }
    return 0;
}