n = int(input())
v = list(map(float,input().split()))
v_list = sorted(v)
for i in range(n-1):
    a = (v_list[0]+v_list[1])/2
    v_list.append(a)
    v_list = sorted(v_list)
    del(v_list[0])
    del(v_list[1])

    
print(v_list)