#include<stdio.h>
#include<algorithm>
using namespace std;
int a[250000];
int main()
{
    int n;
    scanf("%d",&n);
    for(int i=0;i<n;i++)  scanf("%d",&a[i]);
    nth_element(a,a+n/2,a+n);
    if(n&1)   printf("%d.0\n",a[n/2]);
    else {
         nth_element(a,a+n/2,a+n/2);
         double ans = (double)1.0*(a[n/2-1]+a[n/2])/2;
         printf("%.1f\n",ans);
    }
//    system("pause");
}