#include<bits/stdc++.h>
using namespace std;
int main()
{
	int n;
	double s;
	cin>>n;
	int a[105];
	for(int i=0;i<n;i++)
	{
		cin>>a[i];
	}
	for(int i=1;i<=n-1;i++)
	{
		for(int j=0;j<=n-i-1;j++)
		{
			if(a[j]>a[j+1])
			{
				swap(a[j],a[j+1]);
			}
		}
	}
	if(n%2==0)
	{
		s=a[(n/2-1)]+a[(n/2)]*2.0;
	}
	else
	{
		s=a[n/2]/1.0;
	}
	printf("%.1f",s);
	return 0;
} 
/**************************************************************
	Problem: 1233
	User: wangyuxin
	Language: C++
	Result: Wrong Answer
****************************************************************/