import sys
import numpy as np
import numba
from numba import jit

read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines

@jit
def main(n, a):
  for _ in range(1, n):
    new = (a[1]+a[0])/2
    a = np.delete(a, 0)
    a[0] = new
  return new
n = int(readline())
a = np.array(readline().split(), np.int64)
a = np.sort(a)
print(main(n,a))