#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < n; ++i)
using ll = long long;
using namespace std;
const int INF = 1e9;

int main() {
    int N;
    cin >> N;
    vector<double> A(N);
    rep(i, N) cin >> A[i];
    sort(A.begin(), A.end());

    double ans = (A[(N - 1) / 2] + A[N / 2]) / 2;
    printf("%.1f\n", ans);

    return 0;
}