namespace AtCoder;

#nullable enable

using System.Numerics;

static class Extensions
{
    public static T[] Repeat<T>(this int time, Func<T> F) => Enumerable.Range(0, time).Select(_ => F()).ToArray();

    public static ulong ToFlag(this int i)
    {
        if (i < 0 || 63 < i) throw new IndexOutOfRangeException();
        return 1UL << i;
    }
    public static bool OfFlag(this ulong value, int i) => (value & ToFlag(i)) > 0;
    public static ulong WithFlag(this ulong value, int i, bool f) => f ? (value | ToFlag(i)) : (value & ~ToFlag(i));
}

class AtCoder
{
    object? Solve()
    {
        var t = Int();
        var ans = new ulong[t];
        for (var i = 0; i < t; i++)
        {
            var n = Int();
            var x = Input<ulong>();
            var c = 0UL;
            for (var j = 0; j < n; j++) c = c.WithFlag(Int(), true);
            ans[i] = Solve2(n, x, c);
        }
        Out(ans);
        return null;
    }

    static ulong Solve2(int n, ulong x, ulong c)
    {
        c &= ~x;
        for (var i = 61; i >= 0; i--)
        {
            if (!c.OfFlag(i)) continue;
            var k = x;
            for (var j = 0; j < i; j++) k = k.WithFlag(j, false);
            var res = k.WithFlag(i, true) - x;
            if (k > 0) res = Math.Min(res, x - (k - 1));
            return res * 2;
        }
        return 0;
    }

    public static void Main() => new AtCoder().Run();
    public void Run()
    {
        var res = Solve();
        if (res != null)
        {
            if (res is bool yes) res = yes ? "Yes" : "No";
            sw.WriteLine(res);
        }
        sw.Flush();
    }

    string[] input = Array.Empty<string>();
    int iter = 0;
    readonly StreamWriter sw = new(Console.OpenStandardOutput()) { AutoFlush = false };

    string String()
    {
        while (iter >= input.Length) (input, iter) = (Console.ReadLine()!.Split(' '), 0);
        return input[iter++];
    }
    T Input<T>() where T : IParsable<T> => T.Parse(String(), null);
    int Int() => Input<int>();
    void Out(object? x, string? separator = null)
    {
        separator ??= Environment.NewLine;
        if (x is System.Collections.IEnumerable obj and not string)
        {
            var firstLine = true;
            foreach (var item in obj)
            {
                if (!firstLine) sw.Write(separator);
                firstLine = false;
                sw.Write(item);
            }
        }
        else sw.Write(x);
        sw.WriteLine();
    }
}