#include<bits/stdc++.h>
#include <unordered_map>
using namespace std;
#define MAXN ((int) 2e5)

const int N = 1e5 + 10;
const int M = 5e4 + 10;
typedef long long ll;
typedef double db;
typedef pair<int, int>pii;
typedef pair<long, long>pll;
int dx[4] = { 0, 1, 0, -1 }, dy[4] = { 1, 0, -1, 0 };
const int mod = 1e9 + 7;
inline long long read()
{
	long long w = 1;
	long long q = 0;
	char ch = ' ';
	while (ch != '-' && (ch < '0' || ch>'9')) ch = getchar();
	if (ch == '-') w = -1, ch = getchar();
	while (ch >= '0' && ch <= '9')
		q = q * 10 + ch - '0', ch = getchar();
	return w * q;
}
int n, m;
long long arr[N];
long long brr[N];
int check(long long mid,long long a)
{
	if (brr[mid] > a)
		return 1;
	else return 0;
}
void solve()
{
	
	cin >> n >> m;
	memset(arr, 0, sizeof(arr));
	memset(brr, 0, sizeof(brr));
	for (int i = 1; i <= n; i++)
		cin >> arr[i];
	for (int i = 1; i <= m; i++)
	{
		cin >> brr[i];
	}
	sort(arr + 1, arr + n + 1);
	sort(brr + 1, brr + m + 1);
	int ans = 0;
	long long flag = 0;
	for (int i = 1; i <= n; i++)
	{
		if (arr[i] == arr[i - 1]) continue;
		long long l = 1;
		long long r = m;
		while (l < r)
		{
			long long mid = (l+r+1) / 2;
			if (check(mid,arr[i]))
			{
				r = mid-1;
			}
			else
			{
				l = mid;
			}
		}
		if (brr[l] != arr[i])
		{
			ans++;
			
		}

	}
	if (ans == 0)cout << "Impossible" << endl;
	else cout << ans << endl;

	

	
}
int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	int tcase = 1;
	cin >> tcase;
	while (tcase--)
		solve();
	return 0;

}