import java.io.*;
import java.util.*;
import java.util.stream.*;

class Process {
    private int[] A;

    Process(int[] A) {
        this.A = A;
    }

    double getResult() {
        int[] sortedA = IntStream.of(A).sorted().toArray();

        int halfOfLength = A.length / 2;

        if(A.length % 2 == 1) {
            return (double)sortedA[halfOfLength];
        }

        return (((double)sortedA[halfOfLength - 1] + sortedA[halfOfLength]) / 2);
    }
}

public class Main {
    public static void main(String[] args) throws IOException {
        var bufferedReader = new BufferedReader(new InputStreamReader(System.in));
        var printWriter    = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));

        // 入力
        int N = Integer.parseInt(bufferedReader.readLine().trim());

        int[] A = Stream.of(bufferedReader.readLine().trim().split("[ ]+")).mapToInt(Integer::parseInt).toArray();

        // 処理および出力
        printWriter.println((new Process(A)).getResult());
        
        bufferedReader.close();
        printWriter.close();
    }
}