#include <iostream>
#include <stdio.h>
#include <array>

using namespace std;

double a_1;
double s_n;
std::array<double , 10> arr ;

double fib(int i){
  double f[i];

  if(i ==1){
    
  }else if(i % 2 == 0){
    arr[i] = arr[i-1] * 2;
  }else{
    arr[i] = arr[i-1] / 3;
  }
  return arr[i];
}

int main(void){

  std::cin >> a_1;
  arr[1] = a_1;
  scanf("%lf", &a_1);

  for(int i = 1; i <= 10; i++){
    s_n += fib(i);
    if(i == 10){
      printf("%lf", s_n);
    }
  }

  return 0;
}
