#include<bits/stdc++.h>
using namespace std;

int main(){
	int n;
	cin >> n;
	vector<int> a;
	int b;
	for(int i = 0; i < n; i++){
		cin >> b;
		a.push_back(b);
	}
	sort(a.begin(), a.end());
	double ans;
	if(n % 2 == 0){
		ans = (a[n / 2] + a[(n / 2) - 1]) / 2.;
	}else{
		ans = (double)a[n / 2];
	}
	printf("%.10f\n", ans);
}