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

int main() {
    int N;
    cin >> N;
    vector<int> h(N);
    rep(i,N) cin >> h[i];
    double ans = h[0];
    sort(h.begin(),h.end());
    for(int i =1;i<N;i++){
       (double)ans = (ans +h[i])/2;
    }
    
    cout<< ans <<endl;
    return 0;    
}