#include <bits/stdc++.h>

using namespace std;

int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);

  int n;
  cin >> n;
  double ret = 4 * pow(3.0/4, n);
  cout << fixed << setprecision(15) << ret << endl;
  
  return 0;
}