N = int(input())
value_list = input().split()
value_list.sort()
#value_list.reverse()
#print(value_list)
for i in range(N):
	if i == 0:
		new_value = float(value_list[i])
	else:
		new_value = (new_value + float(value_list[i])) / 2

print(new_value)