COALESCE

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

const int N = 1e5 + 5;

int n;
int a[N];

void solve() {
    if(n == 1) {
        cout << a[1];
        return;
    }

    double ans = (double)(a[1] + a[2]) / 2.000000;
    for(int i = 3; i <= n; ++i) {
        ans = ((double)a[i] + ans) / 2.000000;
    }

    cout << fixed << setprecision(6) << ans << '\n';
}

int main() {
#ifdef DN
    freopen("in.txt", "r", stdin);
#endif
    freopen("COALESCE.inp", "r", stdin);
    freopen("COALESCE.out", "w", stdout);
    ios_base::sync_with_stdio(false);
    cin.tie(NULL); cout.tie(NULL);

    cin >> n;
    for(int i = 1; i <= n; ++i)
        cin >> a[i];
    sort(a + 1, a + n + 1);

    solve();

    return 0;
}