#include <bits/stdc++.h>
#define pb emplace_back
#define fst first
#define scd second
#define mkp make_pair
#define mems(a, x) memset((a), (x), sizeof(a))

using namespace std;
typedef long long ll;
typedef double db;
typedef unsigned long long ull;
typedef long double ldb;
typedef pair<int, int> pii;

namespace IO {
    char ibuf[(1 << 20) + 1], *iS, *iT, obuf[(1 << 20) + 1], *oS = obuf;
#define writesp(x) write(x), pc(' ')
#define writeln(x) write(x), pc('\n')
#define gh() (iS == iT ? iT = (iS = ibuf) + fread(ibuf, 1, (1 << 20) + 1, stdin), (iS == iT ? EOF : *iS++) : *iS++)
	template<typename T = int>
    inline T read() {
        char ch = gh();
        T x = 0;
        bool t = 0;
        while (ch < '0' || ch > '9') t |= ch == '-', ch = gh();
        while (ch >= '0' && ch <= '9') x = (x << 1) + (x << 3) + (ch ^ 48), ch = gh();
        return t ? ~(x - 1) : x;
    }
    inline void flush () {
    	fwrite(obuf, 1, oS - obuf, stdout), oS = obuf;
	}
    inline void pc (char ch) {
    	if (oS == obuf + (1 << 20) + 1) flush(); 
    	*oS++ = ch;
	}
	template<typename _Tp>
    inline void write (_Tp x) {
    	static char stk[64], *tp = stk;
    	if (x < 0) x = ~(x - 1), pc('-');
		do *tp++ = x % 10, x /= 10;
		while (x);
		while (tp != stk) pc((*--tp) | 48);
    }
}

using IO::read;
using IO::write;
using IO::pc;
using IO::flush;

const int maxn = 1000100;

int n, m, a[maxn], lsh[maxn], tot, b[maxn];
vector<int> vc[maxn];
vector<pii> qq[maxn];

namespace BIT {
	int c[maxn];
	
	inline void init() {
		for (int i = 0; i <= n; ++i) {
			c[i] = 0;
		}
	}
	
	inline void update(int x, int d) {
		for (int i = x; i; i -= (i & (-i))) {
			c[i] += d;
		}
	}
	
	inline int query(int x) {
		int res = 0;
		for (int i = x; i <= n; i += (i & (-i))) {
			res += c[i];
		}
		return res;
	}
}

void solve() {
	n = read();
	m = read();
	BIT::init();
	tot = 0;
	for (int i = 1; i <= n; ++i) {
		a[i] = read();
		lsh[++tot] = a[i];
		lsh[++tot] = a[i] + 1;
	}
	lsh[++tot] = 1;
	lsh[++tot] = m + 1;
	sort(lsh + 1, lsh + tot + 1);
	tot = unique(lsh + 1, lsh + tot + 1) - lsh - 1;
	for (int i = 1; i <= max(n, tot); ++i) {
		vector<int>().swap(vc[i]);
		vector<pii>().swap(qq[i]);
	}
	for (int i = 1; i <= tot; ++i) {
		vc[i].pb(0);
	}
	for (int i = 1; i <= n; ++i) {
		a[i] = lower_bound(lsh + 1, lsh + tot + 1, a[i]) - lsh;
		vc[a[i]].pb(i);
	}
	for (int i = 1; i <= tot; ++i) {
		vc[i].pb(n + 1);
	}
	for (int i = 1; i <= tot; ++i) {
		for (int j = 1; j < (int)vc[i].size(); ++j) {
			int l = vc[i][j - 1] + 1, r = vc[i][j] - 1;
			if (l > r) {
				continue;
			}
			qq[r].pb(l, lsh[i]);
		}
	}
	for (int i = 1; i <= tot; ++i) {
		b[i] = 0;
	}
	int ans = -1e9;
	for (int i = 1; i <= n; ++i) {
		BIT::update(i, 1);
		if (b[a[i]]) {
			BIT::update(b[a[i]], -1);
		}
		b[a[i]] = i;
		for (pii p : qq[i]) {
			int l = p.fst, x = p.scd;
			ans = max(ans, BIT::query(l) - x);
		}
	}
	writeln(ans);
}

int main() {
	// freopen("I.in", "r", stdin);
	// freopen("my.out", "w", stdout);
	int T = read();
	while (T--) {
		solve();
	}
	flush();
	return 0;
}