n = int(input())
aList = list(map(int, input().split()))
aList.sort()
r = 0
if n % 2 == 1:
    c = n // 2
    r = aList[c]
else:
    c1 = int(n / 2 - 1)
    c2 = int(c1 + 1)
    r = (aList[c1] + aList[c2]) / 2

print(r)