#include <cstdio>
#include<iostream>
 
using namespace std;
  
int main(void){
 
	long double a,before,sum;
 
    while(cin>>a){
		sum=0;
      for(int i=0;i<5;i++){
		  if(i==0) before=a;
		  else before=before/3;
		  sum+=before;
		  before=before*2;
		  sum+=before;
	  }
	  printf("%f\n",sum);
    }
 
    return 0;
}