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

int main(){
	for(;;){
		double a,s[10],max=0;
		cin>>a;
		for(int j=0;j<10;j++){
			if(j==0) s[j]=a;
			
			else if(j%2==1)	s[j]=s[j-1]*2;
			
			else if(j%2==0) s[j]=s[j-1]/3;
		}
		for(int j=0;j<10;j++){
			max+=s[j];
		}
		cout<<setprecision(9)<<max<<endl;
	}
	return 0;
}