#include<bits/stdc++.h>
using namespace std;
typedef signed long long ll;
 
#define REP(i,a,b) for(i=(int)a;i<(int)b;i++)
#define rep(i,n) REP(i,0,n)
#define all(a) (a).begin(), (a).end()

int main(){
	int i,j,k,n,m,l,f,x,y,z; string s;
	cin >> n;
  	vector<int> v(n) = {0};
  	rep(i, n) cin >> v[i];
  	
  	sort(all(v));
  	
  	float ans = v[0];
  	Rep(i,1, n){
      ans += v[i];
      ans /= 2;
    }
  	
  	cout << ans << endl;
}