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

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