Counting Orders

Description:

Input:

Each test contains multiple test cases. The first line contains the number of test cases $$$t$$$ ($$$1 \le t \le 10^4$$$). The description of the test cases follows.

The first line of each test case contains a single integer $$$n$$$ ($$$1 \le n \le 2 \cdot 10^{5}$$$) — the length of the array $$$a$$$ and $$$b$$$.

The second line of each test case contains $$$n$$$ distinct integers $$$a_1$$$, $$$a_2$$$, $$$\ldots$$$, $$$a_n$$$ ($$$1 \le a_i \le 10^9$$$) — the array $$$a$$$. It is guaranteed that all elements of $$$a$$$ are pairwise distinct.

The second line of each test case contains $$$n$$$ integers $$$b_1$$$, $$$b_2$$$, $$$\ldots$$$, $$$b_n$$$ ($$$1 \le b_i \le 10^9$$$) — the array $$$b$$$.

It is guaranteed that the sum of $$$n$$$ over all test cases does not exceed $$$2 \cdot 10^{5}$$$.

Output:

For each test case, output the number of ways to reorder array $$$a$$$ such that $$$a_i > b_i$$$ for all $$$1 \le i \le n$$$, modulo $$$10^9 + 7$$$.

Sample Input:

5
6
9 6 8 4 5 2
4 1 5 6 3 1
3
4 3 2
3 4 9
1
2
1
3
2 3 4
1 3 3
12
2 3 7 10 23 28 29 50 69 135 420 1000
1 1 2 3 5 8 13 21 34 55 89 144

Sample Output:

32
0
1
0
13824