#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
using ld = long double;
using mint = modint998244353;
istream& operator>> (istream& is, mint& x) { long long _x; is >> _x; x = _x; return is; }
ostream& operator<< (ostream& os, const mint& x) { return os << x.val(); }
template<class T, class U>
ostream& operator<< (ostream& os, const pair<T, U>& x) { return os << "{" << x.first << ", " << x.second << "}"; }
#define int ll
#define OVERLOAD_REP(_1, _2, _3, name, ...) name
#define REP2(i, l, r) for (int i = (int)(l); i < (int)(r); ++i)
#define REP1(i, n) REP2(i, 0, n)
#define rep(...) OVERLOAD_REP(__VA_ARGS__, REP2, REP1)(__VA_ARGS__)
#define RREP2(i, r, l) for (int i = (int)(r)-1; i >= (int)(l); --i)
#define RREP1(i, n) RREP2(i, n, 0)
#define rrep(...) OVERLOAD_REP(__VA_ARGS__, RREP2, RREP1)(__VA_ARGS__)
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
#define pb push_back
#define mp make_pair
#define mt make_tuple
const int INF = 1LL << 61;
const int MOD = 998244353;
const int MOD1 = 1e9 + 7;
template<class T> inline bool chmax(T &a, T b) { return a < b ? a = b, 1 : 0; }
template<class T> inline bool chmin(T &a, T b) { return a > b ? a = b, 1 : 0; }
template<class T> T pow(T a, T b, T m) { return b ? b&1 ? a*pow(a, b^1, m)%m : pow(a*a%m, b>>1, m)%m : 1; }
template<class T> T pow(T a, T b) { return b ? b&1 ? pow(a, b^1)*a : pow(a*a, b>>1) : 1; }
template<class... T> inline void input(T&... a) { ((cin >> a), ...); }
template<class T, class... U> inline void print(const T& a, const U&... b) { cout << a; ((cout << " " << b), ...); }
template<class T, class... U> inline void println(const T& a, const U&... b) { print(a, b...); cout << endl; }
inline void println() { cout << endl; }
template<class T> inline void print(vector<T>& A) { rep(i, A.size()) if (i) print("", A[i]); else print(A[i]); }
template<class T> inline void println(vector<T>& A) { print(A); cout << endl; }
const int di[4] = {-1, 0, 1, 0};
const int dj[4] = {0, -1, 0, 1};

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    
    int T;
    input(T);
    rep(t, T) {
    	int N, X;
    	input(N, X);
    	vector<int> C(N);
    	rep(i, N) input(C[i]);
    	
    	vector<int> A(N), B(N);
    	rep(i, N) {
    		int c = C[i];
    		if ((X >> c) & 1) {
    			A[i] = X;
    			B[i] = X;
    		} else {
	    		A[i] = X - ((X & ((1LL << c) - 1)) + 1);
	    		B[i] = X + ((1LL << c) - (X & ((1LL << c) - 1)));
    		}
    	}
    	rep(i, N) {
    		if (A[i] < 0) A[i] = -INF;
    		if (B[i] < 0) B[i] = -INF;
    	}
    	
    	int ans = INF;
    	rep(i, N) {
    		int min_value = A[i];
    		int max_value = X;
    		rep(j, N) {
    			if (min_value <= A[j]) continue;
    			chmax(max_value, B[j]);
    		}
    		chmin(ans, max_value - min_value);
    	}
    	{
    		int min_value = X;
    		int max_value = X;
    		rep(j, N) {
    			if (min_value <= A[j]) continue;
    			chmax(max_value, B[j]);
    		}
    		chmin(ans, max_value - min_value);
    	}
    	println(ans * 2);
    }
}