#include <bits/stdc++.h>
using namespace std;
struct Gmx{
    vector<int> val,cnt;
    int n,mx;
    Gmx(int _n=0):n(_n){
        val.resize(n+1);
        cnt.resize(n+1);
        cnt[0]=n;
        mx=0;
    }
    void add(int x){
        cnt[val[x]]--;
        val[x]++;
        cnt[val[x]]++;
        mx=max(mx,val[x]);
    }
    void del(int x){
        cnt[val[x]]--;
        val[x]--;
        cnt[val[x]]++;
        if(cnt[mx]==0)mx--;
    }
    int getmax(){
        return mx;
    }
};
void gmax(int &x,int y){
    if(y>x)x=y;
}
const int N=600;
void solve()
{
    int n;cin>>n;
    // int n=1e5;
    map<int,int> ma;
    vector<int> a(n+1);
    for(int i=1;i<=n;i++){
        cin>>a[i];
        // a[i]=rand();
        ma[a[i]]=1;
    }
    int cnt=0;
    vector<int>id{0};
    for(auto &it:ma)it.second=++cnt,id.push_back(it.first);
    vector<vector<int>> ve(cnt+1);
    for(int i=1;i<=n;i++)a[i]=ma[a[i]],ve[a[i]].push_back(i);
    vector<int> ans(cnt+1);
    for(int i=1;i<=cnt;i++)ans[i]=(int)ve[a[i]].size();
    for(int t=1;t<=N;t++){
        Gmx sol(n+1),sol2(n+1);
        for(int i=1;i<=n;i++)sol2.add(a[i]);
        int j=0;
        while(sol.mx<t&&j<n){++j;sol.add(a[j]);sol2.del(a[j]);}
        if(sol.mx!=t)break;
        for(int i=1;i<=n;i++){
            if(i>0)gmax(ans[a[i-1]],sol2.val[a[i-1]]+t);
            sol.del(a[i]);
            while(sol.mx<t&&j<n){
                j++;
                gmax(ans[a[j]],sol2.val[a[j]]+t);
                sol.add(a[j]);
                sol2.del(a[j]);
            }
            sol2.add(a[i]);
            if(sol.mx!=t)break;
        }
    }
    for(int z=1;z<=cnt;z++)if((int)ve[z].size()>=N){
        vector<int>sum(n+1);
        for(int i=1;i<=n;i++){
            sum[i]=sum[i-1]+(a[i]==z);
        }
        vector<int>pr(cnt+1),now(cnt+1);
        for(int i=1;i<=n;i++)if(a[i]!=z){
            now[a[i]]+=sum[i]-sum[pr[a[i]]];
            // cout<<"z="<<z<<" i="<<i<<" now="<<now[a[i]]<<" ans="<<(int)ve[a[i]].size()+now[a[i]]<<endl;
            gmax(ans[a[i]],(int)ve[a[i]].size()+now[a[i]]);
            now[a[i]]--;
            if(now[a[i]]<0)now[a[i]]=0;
            pr[a[i]]=i;
        }
        pr=vector<int>(cnt+1,n);
        now=vector<int>(cnt+1,0);
        for(int i=1;i<=n;i++)if(a[i]!=z){
            now[a[i]]+=sum[pr[a[i]]]-sum[i];
            // cout<<"z="<<z<<" i="<<i<<" now="<<now[a[i]]<<" ans="<<(int)ve[a[i]].size()+now[a[i]]<<endl;
            gmax(ans[a[i]],(int)ve[a[i]].size()+now[a[i]]);
            now[a[i]]--;
            if(now[a[i]]<0)now[a[i]]=0;
            pr[a[i]]=i;
        }
    }
    int max_ans=*max_element(ans.begin(),ans.end());
    cout<<max_ans<<"\n";
    for(int i=1;i<=cnt;i++)if(ans[i]==max_ans)cout<<id[i]<<"\n";
}
int main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);
    int T;cin>>T;while(T--)solve();
    return 0;
}