#include "bits/stdc++.h"
using namespace std;
#define print(x) cout<<x<<endl;
#define rep(i,a,b) for(int i=a;i<b;i++)
#define REP(i,a) for(int i=0;i<a;i++)
#define printall(n,array) for(int i=0;i<n;i++){cout<<array[i]<<" ";}cout<<endl;
typedef long long ll;
typedef pair<int, int> PI;
typedef pair<int, PI> V;
typedef vector<int> VE;
const ll mod = 1000000007; //10^9+7

int main(){
  int n;
  cin>>n;
  double ans=4*pow(3,n)/pow(4,n);
  printf("%.15f\n" , ans);
}