#include <bits/stdc++.h>
using namespace std;

int main(){
	int N;
	cin >> N;
	vector<int> v(N);
	for(auto &i:v)cin >> i;
	sort(v.begin(),v.end());
	
	double ans=v[0];
	for(int i=1;i<N;i++)ans=(ans+(double)v[i])/2.0;
	printf("%.9lf\n",ans);
	return 0;
}