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

double an(int n, int a1) {
    if (n == 1) {
        return a1;
    } else if (n % 2 == 0) {
        return an(n - 1, a1) * 2;
    } else {
        return an(n - 1, a1) / 3;
    }
}

int main() {
    double first;
    while (cin >> first) {
        double sum = 0;
        for (int i = 0; i < 10; i++) {
            sum += an(i + 1, first);
        }
        printf("%.8lf\n", sum);
    }
}