#include <bits/extc++.h>
using namespace std;
//using namespace __gnu_pbds;
//#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
#define ll long long
void ALI_72(){
int n;
cin >> n;
double a[n];
for(int i = 0;i < n; ++i) cin >> a[i];
sort(a, a+ n);
for(int i = 1;i < n; ++i){
a[i] = (a[i] + a[i - 1]) / 2;
}
cout << fixed << showpoint << setprecision(6) << a[n - 1] << '\n';
}
signed main()
{
ios_base :: sync_with_stdio(0);
cin.tie(0), cout.tie(0);
int t = 1;
//cin >> t;
while(t--){
ALI_72();
}
}
