#include <bits/stdc++.h>
#include <atcoder/all>
using ll = long long;
#define MOD 1000000007
#define Mod 998244353
const int MAX = 1000000005;
const long long INF = 1000000000000000005LL;
using namespace std;
using namespace atcoder;

void solve() {
    int N;
    ll X;
    cin >> N >> X;
    vector<int> C(N);
    for (int i = 0; i < N; i++) cin >> C[i];
    vector<ll> dl(N), dr(N, INF);
    for (int i = 0; i < N; i++) {
        if (X & (1LL << C[i])) {
            dl[i] = 0;
            dr[i] = 0;
        } else {
            ll nl = X;
            nl = (nl >> C[i]);
            nl = (nl << C[i]);
            nl += (1LL << C[i]);
            dl[i] = nl - X;
            //cout << dl[i] << " " << dr[i] << endl;
            if ((1LL << C[i]) > X) continue;
            ll nr = 0;
            bool found = false;
            for (int j = 0; j < 60; j++) {
                if (found) {
                    if (X & (1LL << j)) nr += (1LL << j);
                } else {
                    if (j > C[i] && (X & (1LL << j))) found = true;
                    else nr += (1LL << j);
                }
            }
            dr[i] = X - nr;
        }
    }

    swap(dl, dr);
    ll ans = 8*INF;
    for (int i = 0; i < N; i++) {
        if (dl[i] == INF) continue;
        ll r = 0;
        for (int j = 0; j < N; j++) {
            if (dl[i] < dl[j]) r = max(r, dr[j]);
        }
        ans = min(ans, (dl[i] + r)*2);
    }
    ll r = 0;
    for (int i = 0; i < N; i++) {
        if (dl[i] > 0) r = max(r, dr[i]);
    }
    ans = min(ans, 2*r);
    cout << ans << endl;
}

int main() {
    ios::sync_with_stdio(0);cin.tie();
    int T;
    cin >> T;
    while (T--) {solve();}
}