#include<iostream>
#include<algorithm>
using namespace std;
int main(void)
{
	int i, n, pa[1010];
	double ans;

	cin >> n;
	for (i = 0; i < n; i++)
		cin >> pa[i];
	sort(pa, pa + n);

ans=(double)(pa[(n-1)/2]+pa[n/2])/2;
	cout << ans << endl;

	return 0;
}