#pragma comment(linker, "/STACK:133217728")
#include<bits/stdc++.h>
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef unsigned short int uns;
#define pii pair<int, int>
#define pll pair<ll, ll>
#define sync ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define FOR(i, a, b) for(int i = (a);i < (b);i++)
#define pb push_back
#define mp make_pair
#define pf push_front
#define fi first
#define se second
#define sqr(a) ((a) * (a))
#define pi 3.1415926535897932
#define eps 0.0000001
#define mod 1000000007
#define vii vector<int>
#define mii map<int, int>
#define mll map<ll, ll>
#define vpp vector<pii>

using namespace std;

int n, m, k;
int x[100005];

int main()
{
    cin >> n;
    multiset<double> s;
    for(int i = 0;i < n;i++){
        int a;
        cin >> a;
        s.insert(a);
    }

    while((int)s.size() > 1){
        double a = *s.begin();
        s.erase(s.begin());
        double b = *s.begin();
        s.erase(s.begin());
        s.insert((a + b) / 2.0);
    }

    cout.precision(9);
    cout << fixed << *s.begin() << endl;

    return 0;
}