#include <iostream>
#include <vector>
#define REP(i,a,b) for(i=a;i<b;i++)
#define rep(i,n) REP(i,0,n)
using namespace std;
int main(void)
{
  int i,j,k,l;
  int n;
  cin >> n;
  double rep = 4;
  rep(i,n) rep *= 3.0/4;
  printf("%.20lf\n",rep);
}