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

int main()
{
  double b;
  while(cin >> b)
    {
      double a = b;
      b *= 2; 
      a += b;
      b /= 3; 
      a += b;
      b *= 2; 
      a += b;
      b /= 3; 
      a += b;
      b *= 2; 
      a += b;
      b /= 3; 
      a += b;
      b *= 2; 
      a += b;
      b /= 3; 
      a += b;
      b *= 2; 
      a += b;
      printf("%.8f\n", a);
    }
  return 0;
}