#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

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);
  }

  reverse(move.begin(), move.end());
  for (int &i: move){
    long long plus = ((x >> i) + 1ll) << i;
    long long minus = ((x >> i) << i) - 1ll;
    if (minus < 0) cout << (plus - x) * 2ll << endl;
    else cout << min(plus - x, x - minus) * 2ll << endl;
    return;
  }
  cout << 0 << endl;
}

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