/* 2890 */

 #include <iostream>

 #include <sstream>

 #include <string>

 #include <map>

 #include <queue>

 #include <set>

 #include <stack>

 #include <vector>

 #include <deque>

 #include <algorithm>

 #include <cstdio>

 #include <cmath>

 #include <ctime>

 #include <cstring>

 #include <climits>

 #include <cctype>

 #include <cassert>

 #include <functional>

 #include <iterator>

 #include <iomanip>

 using namespace std;

 //#pragma comment(linker,"/STACK:102400000,1024000")

 #define sti                set<int>

 #define stpii            set<pair<int, int> >

 #define mpii            map<int,int>

 #define vi                vector<int>

 #define pii                pair<int,int>

 #define vpii            vector<pair<int,int> >

 #define rep(i, a, n)     for (int i=a;i<n;++i)

 #define per(i, a, n)     for (int i=n-1;i>=a;--i)

 #define clr                clear

 #define pb                 push_back

 #define mp                 make_pair

 #define fir                first

 #define sec                second

 #define all(x)             (x).begin(),(x).end()

 #define SZ(x)             ((int)(x).size())

 #define lson            l, mid, rt<<1

 #define rson            mid+1, r, rt<<1|1

 const int maxn = ;

 int a[maxn], b[maxn], aa[maxn];

 int pos[maxn], pn;

 int rrank[maxn], height[maxn], sa[maxn];

 int wa[maxn], wb[maxn], wc[maxn], wv[maxn];

 int n, k, at;

 bool cmp(int *r, int a, int b, int l) {

     return r[a]==r[b] && r[a+l]==r[b+l];

 }

 void da(int *r, int *sa, int n, int m) {

     int i, j, *x=wa, *y=wb, *t, p;

     for (i=; i<m; ++i) wc[i] = ;

     for (i=; i<n; ++i) wc[x[i]=r[i]]++;

     for (i=; i<m; ++i) wc[i] += wc[i-];

     for (i=n-; i>=; --i) sa[--wc[x[i]]] = i;

     for (j=,p=; p<n; j*=, m=p) {

         for (p=,i=n-j; i<n; ++i) y[p++] = i;

         for (i=; i<n; ++i) if (sa[i] >= j) y[p++] = sa[i] - j;

         for (i=; i<n; ++i) wv[i] = x[y[i]];

         for (i=; i<m; ++i) wc[i] = ;

         for (i=; i<n; ++i) wc[wv[i]]++;

         for (i=; i<m; ++i) wc[i] += wc[i-];

         for (i=n-; i>=; --i) sa[--wc[wv[i]]] = y[i];

         for (t=x, x=y, y=t, i=,p=,x[sa[]]=; i<n; ++i)

             x[sa[i]] = cmp(y, sa[i-], sa[i], j) ? p-:p++;

     }

 }

 void calheight(int *r, int *sa, int n) {

     int i, j, k=;

     for (i=; i<=n; ++i) rrank[sa[i]] = i;

     for (i=; i<n; height[rrank[i++]]=k)

     for (k?k--:, j=sa[rrank[i]-]; r[i+k]==r[j+k]; ++k);

 }

 bool judge(int bound) {

     int i = ;

     int pn = ;

     while (i <= n) {

         if (height[i] < bound) {

             at = sa[i-];

             sort(pos, pos+pn);

             int kk = , p = pos[];

             rep(j, , pn) {

                 if (pos[j]-p >= bound) {

                     p = pos[j];

                     ++kk;

                 }

             }

             if (kk >= k)

                 return true;

             pn = ;

             pos[pn++] = sa[i++];

         } else {

             pos[pn++] = sa[i++];

         }

     }

     at = sa[n-];

     sort(pos, pos+pn);

     int kk = , p = pos[];

     rep(j, , pn) {

         if (pos[j]-p >= bound) {

             p = pos[j];

             ++kk;

         }

     }

     if (kk >= k)

         return true;

     return false;

 }

 void printSa(int n) {

     for (int i=; i<=n; ++i)

         printf("%d ", sa[i]);

     putchar('\n');

 }

 void printHeight(int n) {

     for (int i=; i<=n; ++i)

         printf("%d ", height[i]);

     putchar('\n');

 }

 void solve() {

     sort(b, b+n);

     int nn = unique(b, b+n) - b;

     rep(i, , n)

         aa[i] = lower_bound(b, b+nn, a[i]) - b + ;

     aa[n] = ;

     da(aa, sa, n+, nn+);

     calheight(aa, sa, n);

     #ifndef ONLINE_JUDGE

         // printSa(n);

         // printHeight(n);

     #endif

     int l = , r = n, mid;

     int ans = , fr;

     while (l <= r) {

         mid = (l + r) >> ;

         if (judge(mid)) {

             ans = mid;

             fr = at;

             l = mid + ;

         } else {

             r = mid - ;

         }

     }

     printf("%d\n", ans);

     rep(i, , ans)

         printf("%d\n", b[aa[fr+i]-]);

 }

 int main() {

     ios::sync_with_stdio(false);

     #ifndef ONLINE_JUDGE

         freopen("data.in", "r", stdin);

         freopen("data.out", "w", stdout);

     #endif

     int t;

     scanf("%d", &t);

     while (t--) {

         scanf("%d %d", &n, &k);

         rep(i, , n) {

             scanf("%d", &a[i]);

             b[i] = a[i];

         }

         solve();

         if (t)

             putchar('\n');

     }

     #ifndef ONLINE_JUDGE

         printf("time = %d.\n", (int)clock());

     #endif

     return ;

 }