#include <cstdio>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <complex>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <limits>
#include <climits>
#include <cfloat>
#include <functional>
#include <iterator>
#define REP(i,n) for(int(i)=0;(i)<(int)(n);(i)++)
#define REPN(i,n) for(int(i)=1;(i)<(int)(n);(i)++)
#define _abs(x) ((x)>0?(x):-(x))
#define ll  long long 
using namespace std;   
int main()
{
    int t=1;
    int n;
    while(t--)
    {
        
        cin>>n;
        vector<double> v[n];
        REP(i,n)
        {
                cin>>v[i];
        }
        sort(all(v));
        REP(i,n)
        {
                v[i]=(v[i]+v[i-1])/2;
        }
        cout<<v[n-1];
    }
    return 0;
} 