#include <bits/stdc++.h>
//#include <atcoder/all>
using namespace std;
//using namespace atcoder;
//using mint = modint1000000007;
//const int mod = 1000000007;
//using mint = modint998244353;
//const int mod = 998244353;
//const int INF = 1e9;
const long long LINF = 1e18;
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i,l,r)for(int i=(l);i<(r);++i)
#define rrep(i, n) for (int i = (n) - 1; i >= 0; --i)
#define rrep2(i,l,r)for(int i=(r) - 1;i>=(l);--i)
#define all(x) (x).begin(),(x).end()
#define allR(x) (x).rbegin(),(x).rend()
#define P pair<int,int>
template<typename A, typename B> inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; }
template<typename A, typename B> inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; }
long long calcR(long long x, long long c) {
	if (1 & (x >> c))return x;
	long long mask = 0;
	rep2(i, c, 60)mask += 1ll << i;
	x &= mask;
	x += 1ll << c;
	return x;
}
long long calcL(long long x, long long c) {
	if (1 & (x >> c))return x;
	if (x < (1 << (c + 1)))return -LINF;
	long long mask = 0;
	rep2(i, c, 60)mask += 1ll << i;
	x &= mask;
	x -= 1;
	return x;
}
int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	int t; cin >> t;
	while (t--) {
		int n;
		long long x; cin >> n >> x;
		vector<int>c(n);
		rep(i, n)cin >> c[i];
		long long ans = LINF * 2;
		/*rep(i, n) {
			long long r2 = calcR(x, c[i]);
			long long l2 = calcL(x, c[i]);
			cout << i << " " << l2 << " " << r2 << endl;
		}*/
		//break;
		rep(i, n) {
			long long r = calcR(x, c[i]);
			long long l = x;
			rep(j, n) {
				long long r2 = calcR(x, c[j]);
				long long l2 = calcL(x, c[j]);
				if (r2 <= r)continue;
				chmin(l, l2);
			}
			//cout << l << " " << r << endl;
			chmin(ans, (r - l) * 2);
		}
		rep(i, n) {
			long long r = x;
			long long l = calcL(x, c[i]);
			rep(j, n) {
				long long r2 = calcR(x, c[j]);
				long long l2 = calcL(x, c[j]);
				if (l <= l2)continue;
				chmax(r, r2);
			}
			//cout << l << " " << r << endl;
			chmin(ans, (r - l) * 2);
		}
		// all L 
		cout << ans << endl;
	}
	return 0;
}