#include <stdio.h>
#include <stdlib.h>

#define swap(type,x,y) do{type t=x;x=y;y=t;}while(0)

void bubble(int *x,int n)
{
	int i,j;
	
	for(i=0;i<n-1;i++){
		int exchg=0;
		for(j=n-1;j>i;j--)
			if(x[j-1]>x[j]){
				swap(int,x[j-1],x[j]);
				exchg++;
			}
		if(exchg==0)break;
	}
}

int main(void){
	
	int i,n;
	int *x;
	float f;
	
	scanf("%d",&n);
	x=calloc(n, sizeof(int));
	
	for(i=0;i<n;i++){
		scanf("%d",&x[i]);
	}
	
	bubble(x,n);
	
	if(n%2==0)
		f=(x[n/2]+x[n/2-1]);
	else
		f=x[n/2];
	
	printf("%.1f\n",f/2);
	
	return 0;
}