#include<bits/stdc++.h>
#define rep(i,n)for(int i=0;i<n;++i)
#include<string>
using namespace std;

int main() {
	int n;
	cin >> n;
	vector<int>v(n);
	rep(i, n) {
		cin >> v[i];
	}
	sort(v.begin(), v.end());
	double ans = v[0];
	for (int i = 1;i < n;++i) {
		ans = (ans + v[i]) / 2;
	}
	print("%,10\n", ans);
	return 0;
}