import java.util.Arrays;
import java.util.Scanner;
public class No275 {
    public static void main(String[] args) {
        // 標準入力
        Scanner sc = new Scanner(System.in);
            
        int n = sc.nextInt();
        int[] a = new int[n];
        float result;
        
        for (int i = 0; i < n; i++) {
            a[i] = sc.nextInt();
        }
        Arrays.sort(a);
        
        if (n % 2 == 0) {
            result = (a[n / 2] + a[n / 2 - 1]) / 2.0f;
        } else {
            result = a[n / 2];
        }
        System.out.println(result);
    }
}