#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
typedef long long ll;
typedef pair<ll, int> P;

const int MAX_N = 60;
int N;
ll X, lb, 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];
    vector<P> shops;
    for (int i = 0; i < N; i++) {
        ll tmp = (1LL << c[i]);
        if (X & tmp)
            continue;
        ll q = X / tmp;
        shops.push_back(make_pair((q + 1) * tmp, -c[i]));
    }
    if (shops.empty()) {
        cout << 0 << endl;
        return;
    }
    sort(shops.begin(), shops.end(), greater<P>());
    shops.push_back(make_pair(X, 0));
    lb = X; ans = shops[0].first * 2;
    for (int i = 0; i + 1 < shops.size(); i++) {
        ll tmp = (1LL << c[i]);
        ll q = X / tmp;
        if (q == 0)
            break;
        ll pos = (q - 1) * tmp + (tmp - 1);
        lb = min(lb, pos);
        ans = min(ans, (shops[i + 1].first - lb) * 2);
    }
    cout << ans << endl;
}