n = int(input())
vi = list(map(int,input().split()))
if n%2 == 0:
    mean = sum(vi)/len(vi)
    print(mean)
else:
    vi.sort()
    saidai = vi.pop(-1)
    mean = sum(vi)/len(vi)
    ans = (mean+saidai)/2
    print(ans)
