#--------------------------------------------------
import strutils, sequtils, math, algorithm, tables, sets, lists, intsets, critbits, future
proc readSeq(): seq[string] =
    stdin.readLine.split
proc readSeqInt(): seq[int] =
    stdin.readLine.split.map(parseInt)
proc readInt1(): int =
    stdin.readLine.parseInt
proc readInt2(): (int, int) =
    let a = readSeq().map(parseInt)
    return (a[0], a[1])
proc readInt3(): (int, int, int) =
    let a = readSeq().map(parseInt)
    return (a[0], a[1], a[2])
proc readInt4(): (int, int, int, int) =
    let a = readSeq().map(parseInt)
    return (a[0], a[1], a[2], a[3])
#--------------------------------------------------
var n = readInt1()
var v = readSeq().map(parseFloat)
v.sort()
for i in 1..n-1:
    v[i] = (v[i] + v[i-1]) / 2
echo v[^1]