#include <iostream>
#include <vector>

using namespace std;

// 負の方向へ移動する距離を全探索し、正の方向へ移動する距離を最小化する

void solve(){
  int n;
  long long x;
  cin >> n >> x;
  vector<int> c(n);
  for (int &i: c) cin >> i;
  vector<int> move;
  for(int i: c){
    if (!(x & (1ll << i))) move.push_back(i);
  }
  if (move.size() == 0){
    cout << 0 << endl;
    return;
  }
  long long ans = 1ll << 61;
  for (int i = 0; i <= (int)move.size(); i++){
    long long minus;
    if (i == (int)move.size()) minus = x;
    else minus = ((x >> move[i]) << move[i]) - 1ll;
    if (minus < 0) continue;
    long long plus = x;
    for (int &j: move){
      long long p = ((x >> j) + 1ll) << j;
      long long m = ((x >> j) << j) - 1ll;
      if (minus <= m) continue;
      if (plus < p) plus = p;
    }
    if (ans > (plus - minus) * 2ll) ans = (plus - minus) * 2ll;
  }
  cout << ans << endl;
}

int main(){
  int t;
  cin >> t;
  while(t--) solve();
}