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

#0, 1, 2　→　N//2 = 1　ans=1
#0, 1, 2, 3　→ N//2 = 2　ans=(1+2)/2

n = N//2
if N%2:
    ans = A[n]
else:
    ans = (A[n-1]+A[n])/2
print(ans)