#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

vector<int> fRow;
vector<int> sRow;
vector<long long> largCount;
const long long MODVAL = 1000000007;

int main()
{
	int n;
	cin >> n;

	fRow.resize(n + 1);
	for (int i = 0; i < n + 1; i++)
	{
		cin >> fRow[i];
	}

	sRow.resize(n);
	largCount.resize(n);
	for (int i = 0; i < n; i++)
	{
		cin >> sRow[i];
	}

	sort(fRow.begin(), fRow.end());
	sort(sRow.begin(), sRow.end());

	int fPos = 0;
	for (int i = 0; i < n; i++)
	{
		while (fRow[fPos] < sRow[i] && fPos < n)
		{
			fPos++;
		}
		if (fRow[fPos] < sRow[i]) largCount[i] = fPos + 1;
		else largCount[i] = fPos;
	}
	/*
	for (int i = 0; i < n; i++)
	{
		cout << sRow[i] << " " << largCount[i] << endl;
	}
	*/
	long long ans = 1;
	for (int i = 0; i < n; i++)
	{
		ans *= (largCount[i] - i) * (largCount[i] - 1 - i);
		ans %= MODVAL;
	}
	cout << ans;
}