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

void swap (double v[], int i, int j){
	double tmp = v[i];
  	v[i] = v[j];
  	v[j] = tmp;
}

void sort (double v[], int n){
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n-1; j++)
      if (v[j+1] < v[j])
        swap (v, j, j+1);
}

int main(){
  
  int N,count = 0;
  cin >> N;
  double v[N],blend,sum;
  for (int i = 0; i < N; i++)
    cin >> v[i];
  
  sort (v, N);
  
  for(int i = 1; i < N; i++){
    if(v[i]%v[0] == 0)
      count++;
  }
  
  if (count = N)
    blend = v[0];
   else if (N == 2)
   blend = (v[0]+v[1])/2;
  
  else if (N >= 3){
	for(int i = 1; i < N; i++){
      if (i == 1){
        blend = (v[0]+v[1])/2;
        sum = blend;
        blend = 0;
      }
      else {
        blend += (sum + v[i])/2;
        sum = blend;
      }
    }    
  }
  cout << blend << endl;
}