#include <bits/stdc++.h>
#define N 500006
int tree[N];
#define lowbit(x) (x&(-x))
int n, m;

inline int query(int x) {
	int ans = 0;
	for (; x; x -= lowbit(x))
		ans += tree[x];
	return ans;
}

inline void add(int x) {
	for (; x <= n; x += lowbit(x))
		tree[x]++;
}

inline void sub(int x) {
	for (; x <= n; x += lowbit(x))
		tree[x]--;
}

inline void add(int l, int r) {
	add(l);
	if (r != n)
		sub(r + 1);
}
int vis[N];
std::vector<int>id[N];
int nex[N];

struct Ask {
	int r, i;
};
std::vector<Ask>ask[N];
int a[N];

int main() {
	int t;
	scanf("%d", &t);
	while (t--) {
		scanf("%d%d", &n, &m);
		for (int i = 1; i <= n; i++) {
			scanf("%d", a + i);
			id[a[i]].push_back(i);
		}
		int ans = -1;
		for (int j = 1, i; j <= n; j++) {
			i = a[j];
			if (vis[i])
				continue;
			vis[i] = 1;
			if (!id[i].size())
				continue;
			ask[1].push_back({id[i][0] - 1, i});
			ask[id[i][id[i].size() - 1] + 1].push_back({n, i});
			for (int j = 0; j + 1 < id[i].size(); j++) {
				ask[id[i][j] + 1].push_back ({id[i][j + 1] - 1, i});
			}
		}
		for (int i = n; i; i--) {
			int o = nex[a[i]] ? nex[a[i]] : (n + 1);
			nex[a[i]] = i;
			add(i, o - 1);
			for (int j = 0; j < ask[i].size(); j++) {
				if (ask[i][j].r < i)
					continue;
				ans = std::max(ans, query(ask[i][j].r) - i);
			}
		}
		int mex;
		for (mex = 1; vis[mex]; mex++);
		ans = std::max(ans, query(n) - mex);
		printf("%d\n", ans);
		for (int i = 1; i <= n; i++) {
			if (vis[a[i]]) {
				vis[a[i]] = nex[a[i]] = 0;
				std::vector<int>().swap(id[a[i]]);
			}
			std::vector<Ask>().swap(ask[i]);
			tree[i] = 0;
		}
	}
	return 0;
}