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

int main(){
	int i;
	double a[10];
	while(cin >> a[0]){
		double s=a[0];
		for(i=1;i<10;i++){
			if(i%2){
				a[i] = a[i-1]*2;
			}else{
				a[i] = a[i-1]/3;
			}
			s += a[i];
		}
		printf("%.8f\n",s);
	}
	return 0;
}