#include<bits/stdc++.h>
using namespace std;
constexpr int M=5e5+5;
vector<int>pos[M];vector<pair<int,int>>q[M];
int n,m,ans,a[M],tr[M],lsh[M],lst[M];
int read(){
	int x=0,f=1;char ch=getchar();
	while (!isdigit(ch)) {if (ch=='-') f=-1;ch=getchar();}
	while (isdigit(ch)) x=x*10+ch-48,ch=getchar();
	return x*f;
}
void update(int x,int c){while (x) tr[x]+=c,x-=x&-x;}
int query(int x){int res=0;while (x<=n) res+=tr[x],x+=x&-x;return res;}
void solve(){
	n=read();read();ans=0;
	for (int i=1;i<=n;i++) pos[i].push_back(0);
	for (int i=1;i<=n;i++){
		a[i]=lsh[i]=read();
		if (a[i]<=n) pos[a[i]].push_back(i);
	}
	for (int i=1;i<=n;i++) pos[i].push_back(n+1);
	sort(lsh+1,lsh+n+1);m=unique(lsh+1,lsh+n+1)-lsh-1;
	for (int i=1;i<=n;i++) a[i]=lower_bound(lsh+1,lsh+m+1,a[i])-lsh;
	for (int i=1;i<=n;i++)
		for (int j=1;j<pos[i].size();j++)
			q[pos[i][j]-1].push_back({pos[i][j-1]+1,i});
	for (int i=1;i<=n;i++) tr[i]=0;
	for (int i=1;i<=n;i++){
		if (lst[a[i]]) update(lst[a[i]],-1);
		update(i,1);lst[a[i]]=i;
		for (auto [x,y]:q[i]) ans=max(ans,query(x)-y);
	} printf("%d\n",ans);
	for (int i=1;i<=n;i++) q[i].clear(),pos[i].clear(),lst[i]=0;
}
int main(){int T=read();
	while (T--) solve();	
	return 0;
}