#pragma GCC optimize("Ofast", "3", "inline")
#include <bits/stdc++.h>

using i64 = long long;
	
template<typename T>
struct Fenwick {
	int n;
	std::vector<T> a;

	Fenwick(int n) {
		init(n);
	}

	void init(int n) {
		this->n = n;
		a.assign(n, T());
	}

	void add(int x, T v) {
		for (int i = x + 1; i <= n; i += i & -i) {
			a[i - 1] += v;
		}
	}

	T sum(int x) {
		T ans = T();
		for (int i = x; i > 0; i -= i & -i) {
			ans += a[i - 1];
		}

		return ans;
	}

	T rangeSum(int l, int r) {
		return sum(r) - sum(l);
	}
};

void solve() {
	int n, m;
	std::cin >> n >> m;

	std::vector<int> a(n);
	std::vector<std::vector<int>> b(m);
	for (int i = 0; i < n; i++) {
		std::cin >> a[i];
		a[i]--;
		b[a[i]].push_back(i);
	}
	for (int i = 0; i < m; i++) {
		b[i].push_back(n);
	}

	std::vector<std::tuple<int, int, int>> query;
	for (int mex = 0; mex < m; mex++) {
		int lst = 0;
		for (auto x : b[mex]) {
			query.push_back({lst, x, mex});
			lst = x + 1;
		}
	}

	std::sort(query.begin(), query.end(),
		[&](auto lhs, auto rhs) {
			return std::get<1>(lhs) < std::get<1>(rhs);
		});

	Fenwick<int> fen(n);
	std::vector<int> all(m, -1);
	std::vector<std::vector<int>> ans(m);
	int cur = 0;
	for (auto [l, r, mex] : query) {
		while (cur < r) {
			int p = all[a[cur]];
			if (p != -1) {
				fen.add(p, -1);
			}
			fen.add(cur, 1);
			all[a[cur]] = cur;
			cur += 1;
		}
		ans[mex].push_back(fen.rangeSum(l, r));
	}

	int res = -1;
	for (int i = 0; i < m; i++) {
		int mx = *std::max_element(ans[i].begin(), ans[i].end());
		res = std::max(res, mx - i - 1);
	}

	std::cout << res << "\n";
}

int main() {
	std::ios::sync_with_stdio(false);
	std::cin.tie(nullptr);

	int t;
	std::cin >> t;

	while (t--) {
		solve();
	}

	return 0;
}