package main
import("fmt"
"sort")
func main(){
var n,i int
var temp float64
fmt.Scan(&n)
a:=make([]float64,n)
for i=0;i<n;i++{
fmt.Scan(&a[i])
}sort.Float64Slice(a).Sort()
for i=0;i<n-1;i++{
temp=(a[i]+a[i+1])/2
a[i+1]=temp
}fmt.Println(temp)
}
