#include<bits/stdc++.h>
#define int long long
using namespace std;
using i64 = long long;
struct node {
	int l, r;
	i64 dat;
};

struct HisSeg {

	int n, idx;
	vector<int> root;
	vector<node> tr;
	HisSeg(int _n, int m) {
		n = _n;
		idx = 0;
		tr.resize(n * 4 + (__lg(n) + 2) * (m), {});
		root.resize(m + 1);
		root[0] = build(0, n);
	}
	int build(int l, int r) {
		int p = ++idx;
		if(r - l == 1) {
			return p;
		}
		int m = l + r >> 1;
		tr[p].l = build(l, m);
		tr[p].r = build(m, r);
		return p;
	}
	void pull(int p){
		tr[p].dat = tr[tr[p].l].dat + tr[tr[p].r].dat;
	}
	int insert(int nv, int v, int x, int val) {
		return root[nv] = insert(root[v], 0, n, x, val);
	}
	int insert(int p, int l, int r, int x, int val) {
		int q = ++idx;
		tr[q] = tr[p];
		if(r - l == 1) {
			tr[q].dat += val;
			return q;
		}
		int m = l + r >> 1;
		if(x < m) tr[q].l = insert(tr[p].l, l, m, x, val);
		else tr[q].r = insert(tr[p].r, m, r, x, val);
		pull(q);
		return q; 
	}
	int query(int l, int vr){
		return query(root[vr], 0, n, l);
	}
	int query(int p, int l, int r, int x){
		if(r - l == 1){
			return tr[p].dat;
		}
		int m = l + r >> 1;
		if(x < m) return query(tr[p].l, l, m, x) + tr[tr[p].r].dat;
		else return query(tr[p].r, m, r, x);
	}
};

void work()
{
	int n, m;
	cin >> n >> m;
	int ans = -1;
	HisSeg his(m + 1, (n + 1) * 2);
	map<int, int> mp;
	bool flag = false;
	vector<int> a(n + 1), lst(m + 1);
	for(int i = 1; i <= n; ++i){
		cin >> a[i];
		mp[a[i]] = 1;
		if(!lst[a[i]]){
			his.insert(i, i - 1, i, 1);
		}
		else{
			his.insert(n + i, i - 1, lst[a[i]], -1);
			his.insert(i, n + i, i, 1);
		}
		ans = max(ans, his.query(lst[a[i]], i) - a[i] - 1);
//		cout << "PPP " << a[i] << " " << his.query(lst[a[i]] , i) << "\n";
		lst[a[i]] = i;
	}
	for(int i = 1; i <= n + 1; ++i){
		if(lst[i] < n){
			ans = max(ans, his.query(lst[i], n) - i - mp[i]);
//			cout << "HHH : " << i << " " << lst[i] << " " << his.query(lst[i] , n) << "\n";
		}
	}
	cout << ans << "\n";
}
signed main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	int t = 1;
	cin >> t;
	while(t--){
		work();
	}
}