// #pragma GCC optimize("Ofast,no-stack-protector,unroll-loops",
// "omit-frame-pointer", "inline") #pragma GCC
// target("sse,sse2,sse3,ssse3,sse4,sse4.1,sse4.2,popcnt,abm,mmx,avx,avx2,fma,tune=native")
// #pragma GCC option("arch=native", "no-zero-upper") // Enable AVX

/// UH Top
#include <bits/stdc++.h>
#define db(x)   cerr << #x << ':' << (x) << '\n';
#define all(v)  (v).begin(), (v).end()
#define allr(v) (v).rbegin(), (v).rend()
#define int     ll
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
// typedef __int128_t int128;
typedef pair<ll, ll> pii;
typedef pair<ld, ll> pdi;
typedef pair<ld, ld> pdd;
typedef pair<ld, pdd> pdp;
typedef pair<string, ll> psi;
typedef pair<ll, string> pls;
typedef pair<string, string> pss;
typedef pair<ll, pii> pip;
typedef pair<pii, pii> ppp;
typedef complex<ld> point;
typedef vector<point> polygon;
typedef vector<ll> vi;
typedef pair<point, int> ppi;
typedef vector<pii> vpii;
typedef vector<vi> vvi;
#define prec(n)                                                                \
	cout.precision(n);                                                         \
	cout << fixed
const ll mod = (1e9 + 7);
const ld eps = (1e-9);
const ll oo = (ll)(1e18 + 5);
#define pi    acos(-1)
#define MAXN  (ll)(5e5 + 5)
#define fs    first
#define sc    second
#define mid   (L + R) / 2
#define pb    push_back
#define sz(x) (int)((x).size())

int n, m;
struct ABI {
	vector<vector<int>> abi;
	int maxn;
	ABI(int n){
		maxn = n + 5;
		abi.resize(maxn);
	}

	void update(int p, int v) {
		while (p < maxn) {
			abi[p].push_back(v);
			p += (p & -p);
		}
	}

	void build(vector<int> &a) {
		int n = a.size();
		for (int i = 0; i < n; i++)
			update(i + 1, a[i]);
		for (int i = 0; i < maxn; i++)
			sort(all(abi[i]));
	}

	int query(int p, int l, int r) {
		int ans = 0;
		while (p) {
			ans += upper_bound(all(abi[p]), r) - lower_bound(all(abi[p]), l);
			p -= (p & -p);
		}
		return ans;
	}

	int query(int l, int r, int vl, int vr) {
		if(r<l)return 0;
		return query(r + 1, vl, vr) - query(l, vl, vr);
	}
};

vi Pos[MAXN];

void problem() {
	cin>>n>>m;
	set<int> Vec;
	vi AntP;
	for(int i=0;i<n;i++){
		int a;cin>>a;
		Vec.insert(a);
		if(sz(Pos[a])){
			AntP.pb(Pos[a].back());
		}else{
			AntP.pb(-1);
		}
		Pos[a].pb(i);
	}
	ABI cosa(n);
	cosa.build(AntP);
	int ans=0;
	for(auto a:Vec){
		for(int i=0;i<sz(Pos[a]);i++){
			int l,r;
			if(i==0){
			  l=0,r=Pos[a][i]-1;
			  ans=max(ans,cosa.query(l,r,-1,l-1)-a);	
			}
			if(i==sz(Pos[a])-1){
			  	l=Pos[a][i]+1,r=n-1;
			  ans=max(ans,cosa.query(l,r,-1,l-1)-a);		
			}else{
			  l=Pos[a][i]+1,r=Pos[a][i+1]-1;
			  	ans=max(ans,cosa.query(l,r,-1,l-1)-a);			
			}
		}
		Pos[a].resize(0);
	}
	cout<<ans<<'\n';
	
}

int32_t main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);

	int tc = 1;
	cin>>tc;
	while (tc--) {
		problem();
	}

	return 0;
}