#include <iostream>
#include <vector>
#include <algorithm>
#include <iomanip>

using namespace std;

int main(int argc, char const* argv[]) {
    int N;
    vector<int> A;
    double ans;

    cin >> N;
    for (int i = 0; i < N; i++) {
        int tmp;
        cin >> tmp;
        A.push_back(tmp);
    }

    sort(A.begin(), A.end());

    if (N % 2 == 0) {
        ans = (A[N/2-1] + A[N/2]) / 2.0;
    } else {
        ans = A[N/2];
    }

    cout << setprecision(2) << ans << endl;
    return 0;
}