// 

#include <bits/stdc++.h>
using namespace std;

using ll = long long;

#define rep(i, n) for (int i=0; i<(int)(n); ++(i))
#define rep3(i, m, n) for (int i=(m); (i)<(int)(n); ++(i))
#define repr(i, n) for (int i=(int)(n)-1; (i)>=0; --(i))
#define rep3r(i, m, n) for (int i=(int)(n)-1; (i)>=(int)(m); --(i))
#define all(x) (x).begin(), (x).end()

const ll LINF = (ll)(2e18);

int main() {
    int t0;
    cin >> t0;
    rep(i0, t0) {
        int n;
        ll x;
        cin >> n >> x;
        vector<int> c(n);
        rep(i, n) cin >> c[i];
        bool zero = true;
        rep(i, n) if (!(x>>c[i]&1)) zero = false;
        if (zero) {
            cout << 0 << endl;
            continue;
        }
        ll sx = x;
        x = x % (1LL<<(c[n-1]+1)) + (1LL << (c[n-1]+1));
        ll r = x, l = x;
        int mci = -1;
        repr(i, n) if (!(x>>c[i]&1)) {
            mci = c[i];
            break;
        }
        r = ((x >> mci) << mci) + (1LL<<mci);
        l = ((l >> mci) << mci) - 1;
        ll res = (r-x)*2;
        if ((x-l) <= sx) res = min(res, (x-l)*2);
        cout << res << endl;
    }
    return 0;
}