1827A.cpp

#include <bits/stdc++.h>
using namespace std;
using ll = long long;

int main()
{
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int t;
    cin >> t;
    while (t--)
    {
        int n;
        cin >> n;
        vector<ll> a(n), b(n);

        for (ll &x : a) cin >> x;
        for (ll &x : b) cin >> x;

        sort(a.begin(), a.end());
        sort(b.begin(), b.end());

        ll comb = 1;
        int j = n - 1;
        for (int i = n - 1; i >= 0; i--) {
            while (j >= 0 && a[j] > b[i]) j--;
            int valid = n - j - 1 - (n - 1 - i); 
            if (valid <= 0) {
                comb = 0;
                break;
            }
            comb *= valid;
            comb=comb%1000000007;
        }

        cout << comb << '\n';
    }
    return 0;
}