#include <bits/stdc++.h>
using namespace std;

int main() {
int N; cin >> N;
vector<double> v(N);
for(int i = 0; i < N ; i++){
  cin >> v[i];
}
sort(v.begin(), v.end());
double a; a = v[0];
for (int j = 1; j < N; j++){
  a = (a + v[j]) / 2 ;
}

cout << a << endl;
}
