#if __INCLUDE_LEVEL__ == 0

#include __BASE_FILE__

void Solve() {
  int n;
  int64_t x;
  IN(n, x);
  vector<pair<int64_t, int64_t>> v;
  while (n--) {
    int c;
    IN(c);
    if (x >> c & 1) {
      continue;
    }
    int64_t y = x;
    y >>= c + 1;
    y <<= c + 1;
    v.emplace_back(y == 0 ? -INF64 : y - 1, y | INT64_C(1) << c);
  }
  ranges::sort(v);
  int64_t ans = INF64;
  int64_t mx = 0;
  for (auto [y, z] : v) {
    SetMin(ans, x - y + mx);
    SetMax(mx, z - x);
  }
  SetMin(ans, mx);
  OUT(2 * ans);
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);

  int t;
  IN(t);
  while (t--) {
    Solve();
  }
}

#elif __INCLUDE_LEVEL__ == 1

#include <bits/stdc++.h>

template <class T> concept Range = std::ranges::range<T> && !std::convertible_to<T, std::string_view>;
template <class T> concept Tuple = std::__is_tuple_like<T>::value && !Range<T>;

namespace std {

istream& operator>>(istream& is, Range auto&& r) {
  for (auto&& e : r) is >> e;
  return is;
}
istream& operator>>(istream& is, Tuple auto&& t) {
  apply([&](auto&... xs) { (is >> ... >> xs); }, t);
  return is;
}

ostream& operator<<(ostream& os, Range auto&& r) {
  auto sep = "";
  for (auto&& e : r) os << exchange(sep, " ") << e;
  return os;
}
ostream& operator<<(ostream& os, Tuple auto&& t) {
  auto sep = "";
  apply([&](auto&... xs) { ((os << exchange(sep, " ") << xs), ...); }, t);
  return os;
}

}  // namespace std

using namespace std;

#define LAMBDA2(x, y, ...) [&](auto&& x, auto&& y) -> decltype(auto) { return __VA_ARGS__; }
#define SetMin(...) LAMBDA2(x, y, y < x && (x = y, 1))(__VA_ARGS__)
#define SetMax(...) LAMBDA2(x, y, x < y && (x = y, 1))(__VA_ARGS__)
#define INF64 (INT64_MAX / 2)
#define IN(...) cin >> forward_as_tuple(__VA_ARGS__)
#define OUT(...) cout << forward_as_tuple(__VA_ARGS__) << '\n'

#endif  // __INCLUDE_LEVEL__ == 1