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

int main(){
        double a;
        double sum;
        while(cin >> a){
                sum = 0;
                for(int i = 1; i <= 10; i++){
                        sum += a;
                        if(i % 2 == 0){
                                a /= 3;
                        } else{
                                a *= 2;
                        }
                cout << setprecision(10);
                }
                cout << sum << endl;
        }
        return 0;
}