from itertools import permutations

N = int(input())
a = list(map(int, input().split()))
b = list(map(int, input().split()))

a.sort()
b.sort(reverse=True)

t = set(a[i] for i in range(N) if a[i] >= b[i])
result = 0
for x in permutations(a):
    if t == set(list(x)[:len(t)]):
        result += 1
print(result)