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

X_sort = sorted(X)
Y_sort = sorted(Y)

rank_X = []
rank_Y = []

for i in range(n):
    for j in range(n):
        if X[i] == X_sort[j]:
            rank_X.append(j+1)
        if Y[i] == Y_sort[j]:
            rank_Y.append(j+1)

d = 0
for i in range(n):
    d += pow((rank_X[i] - rank_Y[i]), 2)
    
Spearman_rank_coef = 1 - 6 * d / (n * (n * n - 1))
print(round(Spearman_rank_coef, 3))