n = int(input())
X = list(map(float, input().split()))
Y = list(map(float, input().split()))

def getRanks(lst):
    arr = sorted(lst)
    ranks = {val:i+1 for i, val in enumerate(arr)}
    return [ranks[val] for val in lst]

Rx = getRanks(X)
Ry = getRanks(Y)

SRCC = 1 - (6*sum([(rx-ry)**2 for rx,ry in zip(Rx, Ry)]))/(n*(n**2-1))

print(round(SRCC, 3))