#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; }
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 = 0;
		rrep(i, n) {
			if (1 & (x >> c[i]))continue;
			long long bit = 1ll << c[i];
			long long f = (x / bit)*bit;
			long long c = f + bit;
			if (0 == f)ans = 2 * (c - x);
			else ans = min(c - x, x - f + 1) * 2;
			break;
		}
		cout << ans << endl;
	}
	return 0;
}