using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static int[] NList => ReadLine().Split().Select(int.Parse).ToArray();
    static int[][] NArr(long n) => Enumerable.Repeat(0, (int)n).Select(_ => NList).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var t = NN;
        var ans = new long[t];
        for (var u = 0; u < t; ++u)
        {
            var p = ReadLine().Split();
            var (n, x) = (int.Parse(p[0]), long.Parse(p[1]));
            var c = NList;
            ans[u] = Shop(n, x, c);
        }
        WriteLine(string.Join("\n", ans));
    }
    static long Shop(int n, long x, int[] c)
    {
        var list = new List<(long l, long r)>();
        var max = x;
        for (var i = 0; i < n; ++i)
        {
            var lx = x;
            if (((lx >> c[i]) & 1) == 0)
            {
                for (var j = 0; j < c[i]; ++j) if (((lx >> j) & 1) != 0) lx ^= 1L << j;
                --lx;
            }
            var rx = x;
            if (((rx >> c[i]) & 1) == 0)
            {
                rx ^= 1L << c[i];
                for (var j = 0; j < c[i]; ++j) if (((rx >> j) & 1) != 0) rx ^= 1L << j;
            }
            if (lx >= 0 && lx != rx) list.Add((lx, rx));
            else max = Math.Max(max, rx);
        }
        if (list.Count == 0) return (max - x) * 2;
        list.Sort((l, r) => r.l.CompareTo(l.l));
        var ans = (max - list[^1].l) * 2;
        while (list.Count > 0)
        {
            max = Math.Max(max, list[^1].r);
            list.RemoveAt(list.Count - 1);
            if (list.Count > 0) ans = Math.Min(ans, (max - list[^1].l) * 2);
            else ans = Math.Min(ans, (max - x) * 2);
        }
        return ans;
    }
}