#include <iostream>
#include <queue>
using namespace std;

int main() {
    int n;
    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    cin >> n;
    priority_queue<int> q;
    int i;
    int x;
    for (i = 1;i <= n / 2 + 1;i++) {
        cin >> x;
        q.push(x);
    }
    for (i = n / 2 + 2;i <= n;i++) {
        cin >> x;
        q.push(x);
        q.pop();
    }
    if (n % 2 == 1) {
        cout << q.top();
    }
    else {
        int a = q.top();
        q.pop();
        int b = q.top();
        printf("%.1f", a / 2.0 + b / 2.0);
    }
}