#include <bits/stdc++.h>
using namespace std;
const int Max = 1001;
int n;
int arr[Max];
int main()
{
    while(cin>>n)
    {
        memset(arr,0,sizeof(arr));
        for(int i=0;i<n;i++)
        {
            cin>>arr[i];
        }
        sort(arr,arr+n);
        double t ;
        if(n%2==0)
        {
            t=((double)arr[n/2]+(double)arr[n/2-1])/2.0;
        }
        else
        {
        t = arr[n/2];
        }
        printf("%.2f\n",t);
    }
}