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

int main()
{
int N;scanf("%d",&N);double ans=0.000000;
vector<int> v(N);
for(int i=0;i<N;i++)scanf("%d ",&v[i]);
sort(v.begin(),v.end());ans=v[0];
for(int i=1;i<N;i++)ans=(ans+v[i])/2.00000;
printf("%f\n",ans);
}