#include"bits/stdc++.h"

using namespace std;

const int N = 1e6 + 10;

struct segment_tree{
	int a[N << 3], ls[N << 3], rs[N << 3], root, cnt;

	#define mid (l + ((r - l) >> 1))

	void push_up(int i) {
		a[i] = a[ls[i]] + a[rs[i]];
	}

	void add(int &i, int pos, int k, int l = 1, int r = 1e9 + 10) {
		if(!i) i = ++cnt;
		if(l == r) {
			a[i] += k;
			return ;
		}
		else if(pos <= mid) add(ls[i], pos, k, l, mid);
		else add(rs[i], pos, k, mid + 1, r);
		push_up(i);
	}

	int query(int &i, int L, int R, int l = 1, int r = 1e9 + 10) {
		if(l > R || r < L) return 0;
		else if(L <= l && R >= r) return a[i];
		else return query(ls[i], L, R, l, mid) + query(rs[i], L, R, mid + 1, r);
	}

}seg;

void solve() {
	seg.root = 0;
	int n, m;
	cin >> n >> m;
	vector<int> a(n + 10, 0), b(n + 10, 0);
	for(int i = 1; i <= n; i++) {
		cin >> a[i];
	}
	map<int, int> mp;
	for(int i = 1; i <= n; i++) {
		b[i] = mp[a[i]];
		mp[a[i]] = i;
		//cout << b[i] << " ";
	}
	//cout << "\n";
	int ans = -1e9 + 10;
	for(int i = 1; i <= n; i++) {
		int l = b[i] + 1;
		int r = i - 1;
		//cout << i << " " << seg.query(seg.root, l, r) << " " << a[i] << "\n";
		if(r - l + 1 > 0) ans = max(ans, seg.query(seg.root, l, r) - a[i]);
		seg.add(seg.root, i, 1);
		if(b[i]) seg.add(seg.root, b[i], -1);
	}
	vector<int> c(n + 10, 0);
	for(int i = 1; i <= n; i++) {
		if(a[i] <= n) c[a[i]]++;
		int k = seg.query(seg.root, i, i);
		//cout << k << " ";
		if(k && i != n) ans = max(ans, seg.query(seg.root, i + 1, n) - a[i]);
	}
	//cout << "\n";
	//cout << ans << "\n";
	for(int i = 1; i <= n + 1; i++) {
		if(!c[i]) ans = max(seg.query(seg.root, 1, n) - i, ans);
	}
	cout << ans << "\n";
}

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