#include<iostream>
#include <algorithm>
using namespace std;

int main() {
  	int n;
  	cin >> n;
  	double numArr[n];
  	int index = 0;
  	while (n != index) {
	  int input;
      cin >> input;
      numArr[index] = input;
      index += 1;
    }
	
  	sort(numArr, numArr + n);
  	
  	for (int i = 0; i < n-1; ++i) {
      	double first = numArr[i] + numArr[i+1]
    	numArr[i+1] = first / 2
    }
  	cout << numArr[n];
  
	return 0;
}
