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

int main() {

  double a;

  while( cin >> a ) {

    double ans = 0.00;
    for ( int i = 0; i < 10; i++ ) {
      ans += a;
      if ( ( i % 2 ) == 0 ) {
	a *= 2;
      }else {
	a /= 3;
      }
    }
    cout << fixed << setprecision(10) << ans << endl;

  }

  return 0;

}