import java.text.DecimalFormat;
import java.util.Arrays;
import java.util.Scanner;

public class No275 {

    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        int count = s.nextInt();
        int[] arr = new int[count];
        for (int i = 0; i < count; i++) {
            arr[i] = s.nextInt();
        }
        Arrays.sort(arr);

        double median;
        if (count % 2 == 0) {
            median = (double) (arr[count / 2] + arr[count / 2 - 1]) / 2;
        } else {
            median = (double) arr[count / 2];
        }
        System.out.println(new DecimalFormat(".#").format(median));
    }
}