#include<bits/stdc++.h>
using namespace std;

const int N=1e6+10;
int n,a[N],root[N],tot,m;

struct Node
{
    int l,r;
    int cnt;
}tr[N*40];
int build(int l,int r)
{
    int p=++tot;
    if(l==r) return p;
    int mid=(l+r)>>1;
    tr[p].l=build(l,mid),tr[p].r=build(mid+1,r);
    return p;
}
int insert(int p,int idx,int l,int r,int x)
{
    int q=++tot;//点分裂
    tr[q]=tr[p],tr[q].cnt+=x;
    if(l<r)
    {
        int mid=(l+r)>>1;
        if(idx<=mid) tr[q].l=insert(tr[p].l,idx,l,mid,x);
        else tr[q].r=insert(tr[p].r,idx,mid+1,r,x);
    }
    return q;
}
int query(int idx,int q,int l,int r)
{
    if(l==r) return tr[q].cnt;
    int mid=(l+r)>>1;
    if(idx<=mid) return query(idx,tr[q].l,l,mid)+tr[tr[q].r].cnt;
    else return query(idx,tr[q].r,mid+1,r);
}

void solve()
{
    cin>>n>>m;
    root[0]=build(1,n);
    vector<int>g[m + 1],last(m+1);
    a[0] = 0, a[n + 1] = 0;
    for (int i = 1; i <= n; i++) cin >> a[i];
    for(int i=0;i<=n + 1;i++)
    {
        g[a[i]].push_back(i);

        if(!last[a[i]]) // 该数据第一次出现 
            root[i]=insert(root[i-1],i,1,n,1);
        else
        {
            int t=insert(root[i-1],last[a[i]],1,n,-1);
            root[i]=insert(t,i,1,n,1);
        }
        last[a[i]]=i;
    }
    int ans=-1;
    for(int i=1;i<=min(n, m);i++)
    {
        g[i].push_back(0);
        g[i].push_back(n+1);
        sort(g[i].begin(),g[i].end());

        for(int j=1;j<(int)g[i].size();j++)
        {
            int l=g[i][j-1]+1,r=g[i][j]-1;
            ans=max(ans,query(l,root[r],1,n)-i);
        }
    }
    cout<<ans<<'\n';
    for(int i=0;i<=n;i++) root[i]=0;
    for(int i=0;i<=tot;i++)
    {
        tr[i]={0,0,0};
    }
    tot=0;
}

signed main()
{
    int T;cin>>T;
    while(T--) solve();
    return 0;
}


/*
1
5 4
1 2 2 3 4
*/