#include <iostream>
#include <algorithm>
using namespace std;
int N, C;
long long A[100000];

void solve()
{
  cin >> N >> C;
  for (int i = 0; i < N; i++)
    cin >> A[i];
  sort(A, A + N);

  // binary search 
  long long low = 0, high = 1000000000, mid, pos = 0;
  while (high >= low)
  {
    mid = (high + low) / 2;
    if (chk(mid))
    {
      low = mid + 1;
      pos = mid;
    }
    else
    {
      high = mid - 1;
    }
  }
  cout << pos << endl;
}

int main()
{
  int T;
  cin >> T;
  while (T--)
    solve();
  return 0;
}