#include <stdio.h>
#include <algorithm>
using namespace std;
//namaega184

int main(){
	int n;scanf("%d",&n);int a[1001];for(int i=0;i<n;i++)scanf("%d",&a[i]);
	sort(a,a+n);
	double ans;
	if(n%2)ans=a[n/2];
	else ans=(a[n/2-1]+a[n/2])/2.0;
	printf("%f\n",ans);
	return 0;
}