#include <bits/stdc++.h>

using namespace std;

#define FOR(i, a, b) for(int i = (a); i < (b); i++)
#define RFOR(i, a, b) for(int i = (a) - 1; i >= (b); i--)
#define SZ(a) int(a.size())
#define ALL(a) a.begin(), a.end()
#define PB push_back
#define MP make_pair
#define F first
#define S second

typedef long long LL;
typedef vector<int> VI;
typedef pair<int, int> PII;
typedef double db;

void solve()
{
	int n, k;
	cin >> n >> k;
	VI a(k), b(k);
	FOR (i, 0, k)
		cin >> a[i];
	FOR (i, 0, k)
		cin >> b[i];
	sort(ALL(a));
	sort(ALL(b));
	int ans = n;
	FOR (i, 0, k)
	{
		vector<PII> c;
		FOR (j, 0, k)
		{
			int x = (b[(i + j) % k] - a[j] + n) % n;
			int y = x == 0 ? 0 : n - x;
			if (x != 0)
				c.PB(MP(x, y));
		}
		if (c.empty())
		{
			ans = 0;
			break;
		}
		sort(ALL(c));
		FOR (j, 0, SZ(c) - 1)
		{
			ans = min(ans, c[j].F + c[j + 1].S + min(c[j].F, c[j + 1].S));
		}
		ans = min(ans, c[0].S);
		ans = min(ans, c[SZ(c) - 1].F);
	}
	cout << ans << '\n';
	
}

int main()
{
	ios::sync_with_stdio(0); 
	cin.tie(0);
	cout << fixed << setprecision(15);
	
	int t;
	cin >> t;
	while (t--)
	{
		solve();
	}
	
	return 0;
}