#include<iostream>
#include<algorithm>

using namespace std;

int main() {
  
  int N,
  int v[51];
  float out = 0;
  
  cin >> N;
  for (int i=0;i<N;i++){
    v[i] = 0;
  }
  sort(v,v+N);
  out = (float)v[0];
  
  for(int i=1; i<N;i++){
    out = (out + v[i]) / 2;
  }
  
  cout << out;
  
  return 0;
}