#coding:utf-8
def alchemy(x, y):
    val = (x+y)/2
    return val

if __name__ == "__main__":
    n = int(input())
    v = list(map(int, input().split()))
    ans = 0

    v_sort = sorted(v)

    for i in range(n-1):
        new_item = alchemy(v_sort[0], v_sort[1])
        del v_sort[0:2]
        v_sort.append(new_item)

    print(v_sort[0])
