package yukicorder;
import java.util.Scanner;

public class QNo275 {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		short n = sc.nextShort();
		short[] a = new short[n+1];
		short[] out = new short[n+1];
		a[0] = -10000;
		out[0] = -10000;
		for(int i=1;i<=n;i++){
			a[i] = sc.nextShort();
		}
		for(short i =n;i>0;i--){
			partHeap(i,a);
		}
		for(short k=n;k>=1;k--){
			out[k] = a[1];
			a[1] = a[k];
			a[k] = -10000;
			partHeap((short)1,a);
		}
		
	    double center = -10000;
	    if(n%2==0) center = (double)(out[n/2] + out[n/2+1])/2;
	    else center = out[n/2+1];
	    System.out.println(center);
		
	}
	
	private static void partHeap(short parent,short[] a){
		short cand = -10000;
		short lr = -1;
		short pare = -10000;
		try{
			pare = a[parent];
			cand = a[parent*2];
			lr = 0;
			if(cand<a[parent*2+1]){
				cand = a[parent*2+1];
				lr = 1;
			}	
		}catch(IndexOutOfBoundsException e){
			if(lr==-1) return;
		}
		if(cand > pare){
			a[parent] = cand;
			a[parent*2+lr] = pare;
			partHeap((short)(parent*2+lr),a);
		}
	}
}