#include <stdio.h>

int sort(int x[],int l){
	int i,j,k;
	for(i=1;i<=l;i++){
		for(j=l;j>=i+1;j--){
			if(x[j-1]>x[j]){
				k=x[j];
				x[j]=x[j-1];
				x[j-1]=k;
			}
		}
	}
	return 0;
}

int main(void) {
	int i,n,k[1024],x;
	double r;
	scanf("%d",&n);
	for(i = 1;i <= n;i++){
		scanf("%d",&k[i]);
	}
	sort(k,n);
	if(n%2){x = (n+1)/2;r = k[x];}
	else{x = n/2;r = (k[x]+k[x+1]);r = r / 2;}
	printf("%lf",r);
	return 0;
}