#include <bits/stdc++.h>
#define ll long long
#define endll '\n';
#define pb push_back
#define all(v) v.begin(), v.end()
using namespace std;

const int mod = 1e9 + 7, N = 1e6;

void solve()
{
  int n, k;
  cin >> n >> k;
  int mx = 0;
  int ar[n + 3];
  for (int i = 1; i <= n; i++)
    cin >> ar[i], mx = max(ar[i], mx);
  string s = to_string(mx);
  for (int i = 1; i <= n; i++)
  {
    string x;
    for (int j = i; j <= min(n, i + k); j++)
    {
      x += to_string(ar[j]);
    }
    if (x.size() > s.size())
    {
      s = x;
    }
    else if (x.size() == s.size())
    {
      s = max(s, x);
    }
  // cout << s << " " << x << endll;
  }

  cout << s << endll;
}

int32_t main()
{
  ios::sync_with_stdio(false);
  cin.tie(0);
  int t = 1;
  cin >> t;
  while (t--)
  {
    solve();
  }
  return 0;
}