def my_sort(a_array):
    a_array.sort()
    a_array.reverse()
    return a_array

def execute(a_array):
    new_array = my_sort(a_array)
    sum_num = (int(new_array.pop(0)) + int(new_array.pop(0))) / 2
    new_array.append(sum_num)
    if len(new_array) == 1:
        print(new_array[0])
    else:
        execute(new_array)

import sys
a = []
for l in sys.stdin:
    a.append(l)

a_array = a[1].split(' ')
execute([int(i) for i in a_array])