#include <bits/stdc++.h>
#define ll long long
using namespace std;
#define rep(i,j) for(int i=0;i<j;i++)
int main(void)
{
	ll N;
	int v[50];
	double ans;
	cin>>N;
	rep(i,N) cin>>v[i];
	sort(v,v+N);
	ans=v[0];
	rep(i,N-1)
		ans=(ans+v[i+1])/2.0;
	}
	cout<<ans<<endl;
    return 0;
}
