#define _CRT_SECURE_NO_WARNINGS
#define debug(l) cerr<<#l<<' '<<l<<'\n';
#include "bits/stdc++.h"
using namespace std;
#define all(pref) pref.begin(), pref.end()
typedef long long ll;
typedef pair<ll, ll> pll;
typedef long double ld;
vector<vector<ll>> gr;
vector<vector<ll>> siz;
vector<ll> clr;
ll ans = 0;
void dfs(ll v, ll p) {
    siz[clr[v]][v] = 1;
    for (ll& u : gr[v]) {
        if (u != p) {
            dfs(u, v);
            siz[0][v] += siz[0][u];
            siz[1][v] += siz[1][u];
        }
    }
    if (siz[1][v] == siz[0][v])ans++;
}
signed main() {
#ifdef _DEBUG
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    ll t;
    cin >> t;
    while (t--) {
        ll n, k;
        cin >> n >> k;
        vector<ll> a(n);
        map<ll, ll> cnt;
        for (ll i = 0; i < n; i++) {
            cin >> a[i];
            cnt[a[i]]++;
        }
        sort(all(a));
        a.resize(unique(all(a)) - a.begin());
        ll ans = -1;
        pll cur;
        n = a.size();
        for (ll l = 0; l < n; l++) {
            if (cnt[a[l]] >= k) {
                ll r = l;
                while (r < n && cnt[a[r]] >= k && a[(r==l?l:r)] - a[(r==l?l:r-1)] <= 1)r++;
                r--;
                if (a[r] - a[l] > ans) {
                    ans = a[r] - a[l];
                    cur = { a[l],a[r] };
                }
                l = r;
            }
        }
        if (ans == -1) {
            cout << ans << '\n';
        }
        else {
            cout << cur.first << ' ' << cur.second << '\n';
        }

    }

}