#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i, s, n) for(int i = (s); i < n; i++)

int main(void) {
	int t;
	cin >> t;

	int n;
	ll x;
	vector<ll> ans;
	rep(i, 0, t) {
		cin >> n >> x;
		vector<ll> c(n);
		rep(j, 0, n) {
			cin >> c[j];
			c[j] = (1LL << c[j]);
		}

		ll res = 0;
		//cout << "t = " << i << endl;
		rep(k, 0, n) {
			//cout << " k = " << k << " c = " << c[k] << endl;
			if ((x & c[k]) == 0) {
				ll temp = 0;
				for (int bit = 0; bit < 60; bit++) {
					temp |= (x & (1LL << bit));
					if (c[k] & (1LL << bit)) {
						res += ((1LL << bit) - temp);
						x += ((1LL << bit) - temp);
					}
				}
				//cout << " temp = " << temp << " res = " << res << endl;
			}
		}
		ans.push_back(res * 2);
	}

	rep(i, 0, ans.size()) {
		cout << ans[i] << endl;
	}

	return 0;
}