N = int(input())
A = map(int, input().split())

A_list = list(A)
A_list = sorted(A_list)

if N % 2 == 0:
    n_1 =  N * 1//2
    n_2 =  N * 1//2 -1
    ans = (A_list[n_1] + A_list[n_2]) / 2


else :
    n =  N * 1//2
    ans = A_list[n]


ans = round(ans, 1)
print(ans)