#include <bits/stdc++.h>
#define ll long long
#define mp make_pair
#define fi first
#define se second
#define pb push_back
#define vi vector<int>
#define pi pair<int, int>
#define mod 998244353
template<typename T> bool chkmin(T &a, T b){return (b < a) ? a = b, 1 : 0;}
template<typename T> bool chkmax(T &a, T b){return (b > a) ? a = b, 1 : 0;}
ll ksm(ll a, ll b) {if (b == 0) return 1; ll ns = ksm(a, b >> 1); ns = ns * ns % mod; if (b & 1) ns = ns * a % mod; return ns;}
using namespace std;
const int maxn = 200005;
const int D = 455;
int n;
int a[maxn];
vi pl[maxn];
int ind[maxn]; // index
int ext[D]; // 
int sum[maxn];
int ans[maxn];
void upd(int a, int b) {
    chkmax(ans[a], b);
}
int main() {
    int t;
    cin >> t;
    while (t--) {
        cin >> n;
        for (int j = 1; j <= n; j++) ans[j] = 0;
        const int S = D - 5;
        vi tr;
        for (int i = 1; i <= n; i++) scanf("%d", &a[i]), tr.pb(a[i]);
        sort(tr.begin(), tr.end());
        for (int i = 1; i <= n; i++)
            a[i] = lower_bound(tr.begin(), tr.end(), a[i]) - tr.begin() + 1;
        for (int i = 1; i <= n; i++) pl[i].clear();
        for (int i = 1; i <= n; i++)
            pl[a[i]].pb(i);
        for (int i = 1; i <= n; i++)
            for (int j = 0; j < pl[i].size(); j++)
                ind[pl[i][j]] = j;
        
        // small small
        for (int j = 0; j < D; j++)
            ext[j] = n + 1;
        auto big = [&](int tp) {
            if (pl[tp].size() >= S)
                return 1;
            return 0;
        };
        auto calans = [&](int tp) {
            // should never call this with big ones!
            if (big(tp)) return 0;
            int res = 0;
            int id = 0;
            for (int j = 0; j < D; j++) {
                int ed = ext[j];
                if (ed > n)
                    break;
                while (id < pl[tp].size() && pl[tp][id] <= ed)
                    id++;
                int nans = pl[tp].size() - id + j;
                chkmax(res, nans);
            }
            return res;
        };
        for (int i = n; i >= 1; i--) {
            int nans = calans(a[i]) + ind[i] + 1;
            upd(a[i], nans);
            for (int j = ind[i]; j < pl[a[i]].size() && j < ind[i] + S; j++)
                chkmin(ext[j - ind[i] + 1], pl[a[i]][j]);
            for (int j = 0; j < D - 1; j++)
                chkmin(ext[j], ext[j + 1]);
        }
        for (int i = 1; i <= n; i++) 
            upd(i, calans(i));
        
        // now do big
        for (int i = 1; i <= n; i++) {
            if (!big(i)) continue;
            for (int j = 1; j <= n; j++)
                sum[j] = (sum[j - 1] + (a[j] == i));
            for (int b = 1; b <= n; b++) {
                if (b == i) continue;
                int mpref = 0;
                int mans = 0;
                for (int j = 0; j < pl[b].size(); j++) {
                    int id = pl[b][j];
                    chkmin(mpref, -sum[id] + j);
                    chkmax(mans, -sum[id] + j + 1 - mpref);
                }
                upd(i, mans + pl[i].size());
            }

            // b outside
            for (int b = 1; b <= n; b++) {
                if (b == i) continue;
                int mpref = 0;
                int mans = 0;
                for (int j = 0; j < pl[b].size(); j++) {
                    int id = pl[b][j];
                    chkmax(mans, sum[id] - j - mpref);
                    chkmin(mpref, sum[id] - j - 1);
                }
                upd(b, mans + pl[b].size());
            }
        }
        int maxans = 0;
        for (int i = 1; i <= n; i++)
            chkmax(maxans, ans[i]);
        cout << maxans << endl;
        for (int i = 1; i <= n; i++)
            if (ans[i] == maxans)
                printf("%d\n", tr[i - 1]);
    }
    return 0;
}
/*
4
5
1 2 3 2 1
5
1 1 3 1 1
6 2 4 2 4 8 8 5
1 2 3 4 5
*/