#include <iostream>
#include <cmath>
#include <set>
using namespace std;
typedef long long ll;
typedef pair<ll, ll> P;

const int MAX_N = 60;
int N;
ll X, lb, ub, ans;
int c[MAX_N];

int t;
void solve();

int main() {
    cin >> t;
    for (int tt = 0; tt < t; tt++)
        solve();
    return 0;
}

void solve() {
    cin >> N >> X;
    for (int i = 0; i < N; i++)
        cin >> c[i];
    set<P, greater<P>> shops;
    lb = X, ub = X;
    for (int i = 0; i < N; i++) {
        ll tmp = (1LL << c[i]);
        if (X & tmp)
            continue;
        ll q = X / tmp;
        if (q % 2)
            shops.insert(make_pair((q + 2) * tmp, -tmp));
        else
            shops.insert(make_pair((q + 1) * tmp, -tmp));
    }
    if (shops.empty()) {
        cout << 0 << endl;
        return;
    }
    ub = shops.begin()->first;
    ans = (ub - X) * 2;
    while (!shops.empty()) {
        ll tmp = shops.begin()->second; shops.erase(shops.begin());
        if (shops.empty())
            ub = X;
        else
            ub = shops.begin()->first;
        tmp *= -2;
        ll q = X / tmp;
        if (q <= 1)
            break;
        if (q % 2)
            q--;
        lb = min(lb, q * tmp - 1);
        ans = min(ans, (ub - lb) * 2);
    }
    cout << ans << endl;
}