#include <iostream>
#include <cstdio>
#include<list>
#include<iomanip>
#include<cmath>
#include<queue>
#include <functional>
#include<stdio.h>
#include<assert.h>
#include<stack>
#include<sstream>
#include <cstdlib>
#include<map>
#include<algorithm>
#include<set>
#include<utility>
#include<memory.h>
#include<string>
#include<vector>
#include<numeric>
#include <bitset>
using namespace std;
#define ll  long long
#define pb push_back
#define fi(ss) freopen (ss,"r",stdin)
#define fo(ss) freopen (ss,"w",stdout)
#define sz(v)               ((ll)((v).size()))
#define all(x)          (x).begin(),(x).end()
#define rep(i, v)       for(ll i=0;i<sz(v);i++)
#define lp(i,n) for(ll i = 0 ; i < n ; ++i)
#define lpab(i, a, b) for(ll i = a; i <= b; i++)
#define lpba(i, b, a) for(ll i = b; i >= a; i--)
#define hash ___hash
#define next ___next
#define prev ___prev
#define left ___left
#define time __time
typedef pair<ll, ll> pii;
#define F first
#define S second
#define MP make_pair
#define vi vector<ll>
#define vvi vector<vi>
#define vpii vector<pii>
#define mpii map<ll, ll> 
#define mpsi map<string, ll>
#define vs vector<string>
#define ld long double
#define vd vector<ld>
#define pie acos(-1)
const ll maxn = 4 * 100005;
#define fastio ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define txtio   freopen("input.txt","r",stdin); freopen("output.txt","w",stdout);
#define OO 1e18

int main()
{
	ll t;
	cin >> t;
	while (t--)
	{
		ll n, k;
		cin >> n >> k;
		vi v(n);
		lp(i, n)
			cin >> v[i];
		string ans = "0";
		lpab(i, 0, n - k - 1)
		{
			string s = "";
			lpab(j, i, i + k)
			{
				s += to_string(v[j]);
			}
			if (lexicographical_compare(all(ans), all(s)))
				ans = s;
		}
		cout << ans << endl;
	}
	return 0;
}