include<bits/stdc++.h>
#define rep(i,n) for (int i= ; i < (n); ++i)
using namespace std;
typedef long long ll;

int main(){
  int n;
  cin >> n;
  vector<int> v(n);
  rep(i,n) {
     cin >> v[i];
  }
  sort(v.begin(), v.end());
  double ans = v[0];
  for ( i = 1; i <n;i++) ans = (ans + v[i))/2;
  printf("%.10f\n",ans);
  return 0;
  }