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

#define f(i,a,b) for (int i = a; i < b; i++)

int main() {
int N; cin>>N;
vector<int> v(N);
f(i,0,N) cin>>v[i];
sort(begin(v),end(v),greater<int>());
ld ans = v.back(); v.pop_back();
while (v.size()) {
ans = (ans+v.back())/2; v.pop_back();
}
cout << setprecision(20) << ans << endl;
return 0;
}