#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<cctype>
#include<cstdlib>
#include<algorithm>
#include<bitset>
#include<vector>
#include<list>
#include<deque>
#include<queue>
#include<map>
#include<set>
#include<stack>
#include<cmath>
#include<sstream>
#include<fstream>
#include<iomanip>
#include<ctime>
#include<complex>
#include<functional>
#include<climits>
#include<cassert>
#include<iterator>
using namespace std;
int n;
vector<int> v;
int main(){
	scanf("%d", &n);
	for (int i = 0; i < n; i++){
		int a;
		scanf("%d", &a);
		v.push_back(a);
	}
	sort(v.begin(), v.end());
	if (n % 2){
		int k = v[n / 2];
		cout << k << endl;
	}
	else{
		double r = v[n / 2] + v[n / 2 - 1];
		r /= 2.0;
		printf("%.6f\n", r);
	}
	return 0;
}