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



int main()
{
int N;
cin>>N;
vector<double>v(N);
for(int i=0;i<N;i++)
{cin>>v[i];}
sort(v.begin(),v.end());
double answer=v[0]+v[1];
answer/=2;
for(int i=2;i<N;i++)
{answer=(answer+v[i])/2;}
cout<<answer<<endl;
}
