import sys
input = sys.stdin.readline

def solve():
    n,x = map(int,input().split())
    c = list(map(int,input().split()))
    ans = float('INF')
    l = []
    for i in c:
        if (x >> i) & 1 == 1:
            continue
        y = x
        y += 1<<i
        for j in range(i):
            if (y >> j) & 1 == 1:
                y -= 1<<j
        z = x
        z -= 1<<i
        if z < 0:
            z = -10**18
        else:
            for j in range(i):
                if (z >> j) & 1 == 0:
                    z += 1<<j
        l.append([z,y])
    #print(l)
    for i in range(len(l)+1):
        if i == len(l):
            z = x
        else:
            z = l[i][0]
        ma = z
        for j in range(len(l)):
            y = l[j][1]
            if z <= y <= x:
                pass
            else:
                ma = max(ma,y)
        ans = min(ans,(ma-z)*2)
        #rint(i,z,y)
    print(ans)
for i in range(int(input())):
    solve()