#include <bits/stdc++.h>
using namespace std;
#define REP(i,n) for (int i = 0; i < n; i++)
typedef long long ll;
// Welcome to my source code!

int main() {
    int n;
    cin >> n;
    int A[n];
    REP(i,n) cin >> A[i];
    double ans = 0;
    if (n%2 == 0) {
        sort(A, A+n);
        int i = 1;
        for (; i < n/2; i++);
        int j = i-1;
        ans = (A[j]+A[i])/2.0;
    } else {
        double sum = 0;
        REP(i,n) sum += A[i];
        ans = sum/n;
    }
    cout << ans << endl;
}