#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i, a, b) for (register int i = a; i <= b; i++)
 
int t, n;
ll cnt[40];
int main()
{
    cnt[1] = 2;
    rep(i, 2, 30) cnt[i] = cnt[i - 1] * 2;
    cin >> t;
    while (t--)
    {
        cin >> n;
        ll cnt1 = 0, cnt2 = 0, ans1 = 0, ans2 = 0;
        for (int i = n; i; i--)
        {
            if ((ans1 <= ans2 && cnt1 < n / 2) || cnt2 == n / 2)
            {
                cnt1++;
                ans1 += cnt[i];
            }
            else
            {
                cnt2++;
                ans2 += cnt[i];
            }
        }
        cout << abs(ans1 - ans2) << endl;
    }
}

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i, a, b) for (register int i = a; i <= b; i++)
 
int t, k, n, a[110];
int vis[110], cnt;
int main()
{
    cin >> t;
    while (t--)
    {
 
        cin >> n >> k;
        cnt = 0;
        rep(i, 1, n) vis[i] = 0;
        rep(i, 1, n)
        {
            cin >> a[i];
            if (!vis[a[i]])
            {
                vis[a[i]] = 1;
                cnt++;
            }
        }
        if (cnt > k)
            puts("-1");
        else
        {
            cout << k * n << endl;
            rep(i, 1, n)
            {
                rep(j, 1, n) if (vis[j]) cout << j << " ";
                for (int j = 1, id = 1; id <= k - cnt; j++)
                    if (!vis[j])
                    {
                        id++;
                        cout << j << " ";
                    }
            }
            cout << endl;
        }
    }
}