#include <bits/stdc++.h>

using namespace std;

int main() {
    double sq[11];
    while (scanf("%lf", &sq[1]) != EOF) {
        double ans = sq[1];

        for (int i = 2; i <= 10; i++) {
            if (i % 2) sq[i] = sq[i - 1] / 3.0;
            else sq[i] = sq[i - 1] * 2.0;
            ans += sq[i];
        }

        printf("%.10f\n", ans);
    }

    return 0;
}
