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

int main() {
	int n;
  	cin>>n;
    float k;
  	priority_queue<float,vector<int>,greater<int>> a;
  	for(int i=0;i<n;i++) {
          cin>>k;
          a.push(k);
    }
    while(a.size()!=1) {
        float x=a.top();
        a.pop();
        float y=a.top();
        a.pop();
        float z = (x+y)/2;
        a.push(z);
    }
    cout<<a.top()<<endl;
}
