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

int main() {
    int n,i,a[1010];
    cin >> n;
    for(i = 0;i < n;i++) cin >> a[i];
    sort(a,a + n);
    cout << (a[n/2]+a[(n-1)/2])/2.0 << endl;
    return 0;
}