/**
*    author:  boutarou
*    created: 02.08.2020 11:32:01
**/

#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i = 0; i < int(n); i++)
using ll = long long;
using P = pair<int, int>;

int main() {
    int n;
    cin >> n;
    vector<int>a(n);
    rep(i,n) cin >> a[i];
    sort(a.begin(), a.end());
    if (n % 2 == 1) cout << a[n / 2] << endl;
    else {
        int res = a[n / 2] + a[n / 2 - 1];
        cout << fixed << setprecision(10) << (double)res / (double)2 << endl;
    }
    return 0;
}