#include <cstdio>
#include <algorithm>
using namespace std;
int N,v[50]; double ans;
int main() {
    scanf("%d",&N); for (int i = 0;i < N;i++) scanf("%d",&v[i]); sort(v,v+N);
    ans = v[0]; for (int i = 1;i < N;i++) ans+=v[i],ans/=2;
    printf("%f\n",ans);
}
