num_N = int(input().rstrip())
data = list(map(int, input().rstrip().split(' ')))

data.sort()

i = num_N // 2
if num_N % 2 == 0:
    median = (data[i-1] + data[i]) / 2
else:
    median = data[i]

print('{0:.1f}'.format(median))