#include<stdio.h>

int main(void){
	int n,i,j,min=1001,tem;
	double mid;

	scanf("%d",&n);/*配列の要素数を入力*/

	int ar[n],re[n];

	for(i=0;i<n;i++) scanf("%d",&ar[i]);/*配列に値を入力*/

	/*arをソートする*/
	for(j=0;j<n;j++){
		/*arの最小値を見つける*/
		for(i=0;i<n;i++){
			if(ar[i] < min){
				min = ar[i];
				tem = i;
			}
		}
		re[j] = min;
		ar[tem] = 1001;
		min = 1001;
	}

	if(n%2 == 0) mid = (re[n/2]+re[n/2-1])/2.0;
	else mid = (double)re[n/2];

	printf("%.2f\n",mid);

	return 0;
}