#include <iostream>
using namespace std;

int main() {
    int n;
    cin>>n;
    int arr[n];
    for(int i=0;i<n;i++)
    {
        cin>>arr[i];
    }

    if(n%2==1)
    {
        cout<<arr[n/2];
    }
    else
    {
        double ans = (arr[(n-1)/2] + arr[n/2])/2.0;
        cout<<ans;
    }
    return 0;
}